Chemistry Unit 1 Worksheet 6 Dimensional Analysis Answers Chemistry Unit 8 Unit 8 Overview Pacing by fbo15485

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									  Chemistry   Unit: 8




                              Unit 8 Overview
                        Pacing: 4 Instructional Weeks
                         Report Period 3:Weeks 7-9
                          Report Period 4: Week 1
  The Balanced Chemical Equation Also Tells Us The Quantities Of Reactants to Use




Key Concepts/Overarching Questions

                   KEY CONCEPT                   OVERARCHING QUESTIONS
Key 1: Balanced chemical equations are          1. What does it mean for a reaction
required to determine the quantities of            to be balanced?
chemicals involved in a reaction.               2. How can we use what we know
                                                   about particles to determine what
                                                   happens during a reaction?
                                                3. What is the relationship between
                                                   reactants and products during a
                                                   chemical reaction?
Key 2: The maximum reaction is achieved         4. What evidence indicates that a
when the reactants are combined in the             reaction is complete?
stoichiometric ratio, from the balanced         5. What would you have to consider
equation.                                          to make more product once a
                                                   reaction is complete?
Key 3: For a chemical reaction to happen,       6. How can we increase the speed
the molecules must come in contact. A              of a reaction?
reaction will happen faster when more
molecules come in contact within a given
time.




                                                                               1
  Chemistry   Unit:8




                                Unit 8 Overview

                               Alignment to Standards

Focus Pennsylvania Standards

3.2.10.A
Apply knowledge and understanding about the nature of scientific and technological
knowledge.
    Compare and contrast scientific theories and beliefs.
    Know that science uses both direct and indirect observation means to study the
      world and the universe.
      Integrate new information into existing theories and explain implied results.
3.2.10.B
Apply process knowledge and organize scientific and technological phenomena in
varied ways.
    Describe materials using precise quantitative and qualitative skills based on
      observations.
    Develop appropriate scientific experiments: raising questions, formulating
      hypotheses, testing, controlled experiments, recognizing variables,
      manipulating variables, interpreting data, and producing solutions.
    Use process skills to make inferences and predictions using collected
      information and to communicate, using space/time relationships, defining
      operationally.
3.2.10.C
Apply the elements of scientific inquiry to solve problems.
    Generate questions about objects, organisms and/or events that can be
      answered through scientific investigations.
    Evaluate the appropriateness of questions.
    Design an investigation with adequate control and limited variables to
      investigate a question.
    Conduct a multiple step experiment.
    Organize experimental information using a variety of analytic methods.
    Judge the significance of experimental information in answering the question.
      Suggest additional steps that might be done experimentally.


                                                                                  2
3.4.10.A
Explain concepts about the structure and properties of matter.
     Describe phases of matter according to the Kinetic Molecular Theory.
     Explain the formation of compounds and their resulting properties using
       bonding theories (ionic and covalent).
     Recognize formulas for simple inorganic compounds.
     Describe various types of chemical reactions by applying the laws of
       conservation of mass and energy.
     Apply knowledge of mixtures to appropriate separation techniques.
  3.4.10.B
Analyze energy sources and transfers of heat.
     Determine the efficiency of chemical systems by applying mathematical
       formulas.
     Use knowledge of chemical reactions to generate an electrical current.
     Evaluate energy changes in chemical reactions.
     Use knowledge of conservation of energy and momentum to explain common
       phenomena (e.g., refrigeration system, rocket propulsion).

Eligible Content

   S11.A.1.1.5
   Analyze or compare the use of both direct and indirect observation as means to
   study the world and the universe: (e.g.behavior of atoms, functions of cells, birth
   of stars).
   S11.A.2.1.3
   Use data to make inferences and predictions, or to draw conclusions,
   demonstrating understanding of experimental limits.
   S11.A.2.1.4
   Critique the results and conclusions of scientific inquiry for consistency and logic.
   S11.A.2.1.5
   Communicate results of investigations using multiple representations.
   S11.C.1.1.6
   Describe factors that influence the frequency of collisions during chemical
   reactions that might affect the reaction rates
        surface area, concentration, temperature
   S11.C.2.1.2
   Describe energy changes in chemical reactions.




                                                                                       3
  Chemistry Unit: 8


                                         Unit 8 Overview
  TEXT AND                                                   ADDITIONAL
ASSOCIATED                                                   RESOURCES
RESOURCES
Chapter 10 pgs        Dimensional Analysis
286 – 299;            Dimensional analysis is explained through the
Chapter 12 pgs        factor-label method. There are six examples with
352 – 375             detailed solutions and a short quiz.
Chapter 18 pgs        http://www.chem.tamu.edu/class/fyp/mathrev/mr-
540 - 548             da.html
Overheads 109,
129, 197, &           All About Mole Calculations
198                   One of the main problems that beginning chemistry
Activities 8.1 –      students have is in doing conversions between
8.7                   grams, moles, and molecules (or atoms.) Learn a
Worksheets 8.1        step by step process to solving mole problems.
– 8.9                 http://misterguch.brinkster.net/molecalculations.html

                      Mole, Molar Mass and Mass Conversions, Examples
                      This page contains three detailed mole conversion
                      examples that are explained in a step by step
                      manner.
                      http://www.800mainstreet.com/6/0006-004-Mole-
                      Mass-Con.htm

                      Molar Mass Calculations and Javascript Calculator
                      Learn how to calculate molar mass of elements and
                      compounds. An on-line calculator is also available
                      to verify your calculations.
                      http://klbproductions.com/yogi/reference/molar.html

                      Chemical Stuff
                      A small site with several very detailed tutorials
                      covering equilibrium calculations and atomic,
                      molecular, and formula mass. In addition there is a
                      formula mass and a percentage composition
                      calculator.
                      http://www.carlton.srsd119.ca/chemical/

                      Stoichiometry Practice
                      This website gives additional practice problems and their solutions.
                      http://www.bishops.k12.nf.ca/Science/chem/2202/worksheets/mass_
                      mole/Stoichiometry%2520Worksheet.htm

                      Catalysts and Enzymes
                                                                                             4
This cross-curricular unit from the NSTA Scope, Sequence & Coordination project uses a
biological process to demonstrate how catalysts can affect reaction rates in chemical processes.
http://dev.nsta.org/ssc/pdf/v4-0969t.pdf

Factors that Affect Reaction Rates
This unit guides students through the process of evaluating the effects of temperature, stirring
and concentration on the rate that chemicals react.
http://dev.nsta.org/ssc/pdf/v4-0967t.pdf

Kinetics and Mechanism
This site probes a students’ understanding of the underlying concepts thru the use of Concept
Tests" rather than algorithmic calculations or vocabulary review. This set of Concept Tests is
suitable for second year students.
http://www.chem.wisc.edu/~concept/kinetics.html


Chemical Reaction Rates
Students will be able to describe the rate of reaction and its units, the factors affecting reaction
rates, and how to write the rate expression for a single-step chemical reaction.
http://texaseducator.com/family/jbouyer/lessons/Science/askew/myc...

Surface Area and Reaction Rate
How does surface area affect reaction rates? Here is an excellent demonstration that illustrates
this.
http://chem.lapeer.org/Chem1Docs/SurfaceAreaRate.html

Reaction Rates: Energy Matters
This website provides illustrated notes that introduce the general principles of reaction rates.
The topics reviewed are: rates of reaction, effects of temperature and concentration on reaction
rates, light reactions, and more.
http://www.hsn.uk.net/resources/HSN11100




                                                                                     5
    Chemistry   Unit: 8

                                   Unit 8 at a Glance
                                    Pacing: 4 weeks
Module     Pacing            Key               Overarching Questions       Student Products

                    Balanced chemical       1. What does it mean for    Worksheets,
                    equations are              a reaction to be         Homework, scientific
                                                                        explanations, Lab
                    required to                balanced?
                                                                        Report
                    determine the           2. How can we use what
                    quantities of              we know about
                    chemicals involved         particles to think
1          6        in a reaction.             about what happens
                                               during a reaction?
                                            3. What is the
                                               relationship between
                                               reactants and products
                                               during a chemical
                                               reaction?
                    The maximum             4. What evidence            Worksheets,
                    reaction is achieved       indicates that a         Homework, Lab
                                                                        Report, Exam
                    when the reactants         reaction is complete?
2          8        are combined in the     5. What would you have
                    stoichiometric ratio,      to consider to make
                    from the balanced          more product once a
                    equation.                  reaction is complete?

                   For a chemical        6. How can we increase     Worksheets,
3         9        reaction to happen        the speed of a         Homework, Lab Report
                                                                    incorporating scientific
                   the molecules must        reaction?
                                                                    explanations
                   come in contact. A
                   reaction will happen
                   faster when more
                   molecules come in
                   contact within a
                   given time.
Required Culminating Project: Students revisit Activity 8.1, determining how they find
quantitative results, to determine how pure each sample is compared to the others.



                                                                                         6
  Chemistry Unit: 8



                          Unit 8 Instructional Pathway

Module 1: SNAPSHOT
                                                 Pacing: 6 days
Objectives:
   1. The student will be able to solve mole-mole, mole - gram, gram-mole or gram-
      gram stoichiometry problems.
CE’s & PE’s:
   Interpret the meaning of a balanced chemical equation.
   Use a balanced chemical equation to calculate the quantities involved in a
        chemical reaction
Text References, Materials & Supplies:

                       Resource                                    Needed Supplies
     Chapter 10 pgs 286 – 299;                       Plastic baggies
     Chapter 12 pgs 352 – 375                        NaHCO3
     Overheads 109 & 129
                                                     Sugar
     Activities 8.1 – 8.3
     Worksheets 8.1 – 8.5                            Vinegar
                                                     Zinc acetate
                                                     Sodium phosphate
                                                     Filter paper
                                                     Funnels
                                                     Beakers
                                                     Drying oven
                                                     Water bottle
                                                     Calcium carbonate
                                                     3 M HCl
                                                     Balloons
                                                     125-Erlenmyer flasks
Instructional Pathway: Students will need to recall how to name and form compounds (from unit 5),
and also tie that in with balancing chemical reactions (from unit 7). From here they are going to
determine what a chemical reaction means and figure out why it has to be balanced. Then we will use
the foundation started in unit 6 to get students to understand that given an amount of a chemical you can
quantitatively determine the amount of product theoretically produced.




                                                                                                   7
Assessments (formative and/or summative): Homework, worksheets, lab report, and Exam


Differentiation: Percentage Yield Calculations




                                                                                       8
  Chemistry   Unit: 8


Module 1: DETAILED
INSTRUCTIONAL PATHWAY


DAY 1
Engage/ Explain: Activity 8.1
Present the students with the problem of a sugar manufacturer making
his product “stretch” by adding bicarbonate of soda. Students are
provided with vinegar as the other reactant and will set up their own
tests and ways to compare and evaluate the three samples.
Students must give clear explanations as to how they came to their
conclusion about which sample contained the most sugar.
Remind students that in order to have a scientific explanation they
need three parts; the claim, evidence, and reasoning behind their
theory.
Challenge students to find a quantitative way to determine the
percentage of bicarbonate of soda in their mixtures. Ask each group
to present and explain their results. Students will most likely
determine that the more bicarbonate of soda added, the greater the
amount of reaction.
Ask what the bubbling signified and try to establish the link between
more bicarbonate of soda and more gas/product. Reactions and the
quantities involved can help determine how much chemical is present.
Homework: Worksheet 8.1 This is a review from unit 6 where
students converted from atoms or molecules to grams for one
substance, concentrating on the factor label method which they have
used throughout the year.
Explain how this is the foundation for this unit, but now we will be
combining the concepts in both units 6 & 7 so that eventually we can
say that this is how much you started with and this is how much of
the product will be formed during the reaction.

Day 2
Expand: Activity 8.2
Review homework.
Use the common everyday reaction of iron rusting to expand the
students’ thinking about chemical reactions. Put out some steel wool
ahead of time (for about a week) and let it sit out. Compare the “old”
steel wool to a new pad to show that the steel wool is crumbly and no
longer has the same original properties as steel wool. Ask students
                                                                         9
what they think happened to the “old” steel wool. Chart some of the
students’ ideas. Then ask them for reasons for their ideas.
After students have had an opportunity to tell you their ideas and
explain their reasons, establish with students that moisture from the
air acts as a catalyst (make them think back to unit 7 to define a
catalyst).
Ask what will determine how much rust is formed. Balance the
equation for the reaction on Activity 8.2 transparency sheets,
modeling the use of circles to represent each atom.
Proceed to work through the chart, first using circles to represent each
atom and build molecules (symbolic representation), then multiply by
Avogadro’s number and then write the amounts out as moles and
finally convert the moles to grams.
 Show that the moles match the balanced chemical equation but that
the grams do not.
Ask students “why not?”
You may want to point out that the rust is heavier than the original
iron.
This is a disconnect for students because it is crumbly and appears
light.
Work through the magnesium carbonate and phosphoric acid example
to again show that the balanced chemical equation gives the number
of moles of each chemical involved. Double and halve the quantities
to show that it is a ratio and that chemicals can be combined in
different quantities but must still maintain the ratio, just as they would
adjust a cookie recipe for a small group or a large party.
Use other examples to show how to use the mole ratio to convert less
obvious quantities of moles.
As you work through the examples ask students to determine what
conversion the question is asking for.
Help the students read and interpret the last problem where they will
need to write their own equation.
 Homework: Worksheet 8.2

Day 3
Review homework. Emphasize the mole ratio.
Copy the sheet labeled Activity 8.3 onto a transparency.
Use it to conduct a guided whole group discussion to solve problems
with moles.
Ask students about some of the important features they need to know

                                                                             10
to solve the problems. Emphasize how understanding moles is key to
doing/understanding the problems. As chemicals need to be weighed
in the lab, we need to convert between moles and grams. Show the
steps so that the problem can be worked as one continuous factor
label problem.
Draw a sequence of steps and the conversion factor that is being used
each time.
Continue to work through the sample problems as guided practice,
involving students, to provide the steps.
Homework: Complete the last few problems for homework.

Day 4
Evaluate: Review homework.
Have students share their answers either on whiteboards in small
groups, or on an Elmo. You will need to try to identify where they are
having difficulties.
Students tend to use the mole ratio when they are determining the
mass and you need to emphasize that the mole conversion step is the
only time that they use the balanced chemical equation.
Help students to read the question carefully and identify what the
question is asking.
Using worksheet 8.4, students should work in groups on sample
mass- mass problems. Have the students write out the sequence for
each problem. Finish the worksheet for homework.

Day 5-6
Have groups share out answers for worksheet 8.4 then move on to
problems that are mass- mole, mole- mass as well as mole-mole and
mass- mass.
Give students practice and try to vary some activities which give
more practice.
Again help students to identify what the question is asking and what
information they have been given. They need to determine when they
have reached the answer. Use white boards for students to share
answers.
More problems: Worksheet 8.4 & Worksheet 8.5

There are two versions of worksheet 8.5 provided. The first version
gives most of the equations but not all of them. If you have students
who have predicted products then they should be able to use this

                                                                         11
version of the problems where some of the equations need to be
formed and balanced by the students. If you had to skip predicting
products due to time constraints you may want to take this
opportunity to ask students what they think the products will be and
review compounds and naming as well.



  It is recommended that you spend 1 period per unit practicing PSSA open-
  ended type questions.




                                                                             12
  Chemistry Unit: 8



                         Unit 8 Instructional Pathway

Module 2: SNAPSHOT
                                              Pacing: 8 days
Objectives:
   1. The student will be able to identify the limiting reactant and the excess reactant.


CE’s & PE’s:
   If the reactants are not combined in the exact mole ratio, then the reaction will
        proceed until the reactant which is present in the least (according to the mole ratio)
        amount is used up. This quantity will determine the amount of products formed.
        There will be excess reactant left over.
Text References, Materials & Supplies:

                      Resource                                  Needed Supplies
     Chapter 10 pgs 286 – 299;                     Plastic baggies
     Chapter 12 pgs 352 – 375                      NaHCO3
     Overhead 129
                                                   Sugar
     Activities 8.4 - 8.6
     Worksheet 8.6 – 8.8                           Vinegar
                                                   Sodium carbonate
                                                   Calcium chloride
                                                   Filter paper
                                                   Funnels
                                                   Beakers
                                                   Drying oven
                                                   Water bottle
                                                   Calcium carbonate
                                                   3 M HCl
                                                   Balloons
                                                   125-Erlenmyer flasks

Instructional Pathway: Students will determine an amount of a chemical needed to react and
determine the amount of product theoretically produced. They will also quantify how much of which
chemical will be left over.



                                                                                             13
Assessments (formative and/or summative): Homework, worksheets, lab report, and Exam


Differentiation: Limiting Reactant calculations




                                                                                       14
  Chemistry   Unit: 8


Module 2: DETAILED
INSTRUCTIONAL PATHWAY
                                                                          Teacher Notes:
                                                                          Differentiation / Scaffolding
                                                                          & Common Misconceptions
Day 7
Explore: Activity 8.4: Does adding more always give more product?
The purpose of this activity is to challenge student’s assumptions that
using more of one reactant will always give more products.
Have students work in groups of 2-3 to complete the activity.
Each group should have three flasks and three balloons. We want
each group to observe the reaction between the different amounts of
calcium carbonate and the hydrochloric acid.
 Ask students what the variable is so that the groups realize that the
amount of hydrochloric acid does not change. When the chemicals
react, carbon dioxide gas is produced, causing the balloons to inflate.
Groups will know right away that the first flask’s balloon didn’t
inflate much, but many students will see the third balloon as bigger
than the second one, when in fact they are the same size. The third
flask will have calcium carbonate left over as an excess reactant. As
you walk around, ask students what the powder in the flasks means
without telling them what an excess reactant is.
Encourage students to write out their explanations, again utilizing the
claim-evidence-reasoning model.

Day 8
Explain/Elaborate: Copy Activity 8.5 onto a transparency.
Use this to begin a class discussion about the activity from the day
before.
Eventually students will say that once the acid was used up then the
reaction stopped.
There was not enough acid to use the extra calcium carbonate.
In the first flask there was not enough powder to use up the acid so
that balloon was not as big.
From this give the real life example of the assembling of a truck and
making peanut butter sandwiches.
Give the definition of an excess reactant and a limiting reagent.
Continue with the remaining examples.
The problems use quantities that match the balanced chemical
equation and so the ones that don’t match up are the excess reagent.
                                                                                          15
Day 9
Explore: Activity 8.6: Varying the quantities of chemicals varies the
yield of a reaction.
Students will add varying quantities of sodium carbonate and calcium
chloride solutions.
Since students will need to wait until the next day for the precipitates
to settle, after the test tubes have been set up, let students begin
worksheet 8.6 and then complete for homework.

Day 10
Explain/ Elaborate: Come back and measure the heights of the
precipitates and record.
 Students will then test the supernatant solutions above the
precipitates to determine the excess reagent present. Help them
reason that if one reagent produces some more reaction then the other
reagent must be present in excess. Ask students to share their
explanations and discuss what took place.

Day 11
Continue any discussion about the lab and worksheet 8.6 and then use
worksheet 8.7 to continue to identify limiting and excess reagents.
Discuss the meaning of the graph.
Make sure students understand why there is a flat spot on the graph,
and that they can explain why the slope of the line is no longer
positive.
Students should also be able to determine what would need to happen
in order to cause the slope of the line to increase again, and be able to
explain why that happens.

Homework: A few more stoichiometry problems.

Day 12
Review sheet worksheet 8.8

Day 13
Test



                                                                            16
Day 14
Mandatory assessment
Ask students to re-visit the sugar contamination lab and see if they
can propose a more quantitative way to rank the mixtures. If time
permits allow them to try their ideas.




                                                                       17
  Chemistry Unit: 8



                         Unit 8 Instructional Pathway

Module 3: SNAPSHOT
                                               Pacing: 6 days
Objectives:
1. The student will be able to set up an experiment to check a hypothesis and discover
the factors which increase the rate of a reaction.

CE’s & PE’s:
    Identify that a reaction will only happen when the reactant molecules collide or
     come in contact
    Define and determine a measure of the rate of a reaction
    Identify the factor that increases the rate of a reaction
Text References, Materials & Supplies:

                      Resource                                     Needed Supplies
     Chapter 18 pgs 540 - 548                      Flasks
     Overheads 197 & 198                           Beakers
     Activity 8.7                                  Graduated Cylinders
     Worksheet 8.9                                 Balances
                                                   Balloons
                                                   Timers
                                                   Scoopulas
                                                   1M HCl
                                                   3M HCl
                                                   6M HCl
                                                   Mossy Zinc
                                                   Powder Zinc
                                                   Granular Zinc
Instructional Pathway: This module connects chemical reactions with kinetics where students
engage with reactions in order to discover what factors can make reactions speed up.

Assessments (formative and/or summative): Homework, worksheets, procedures, lab report


Differentiation: Kinetic Molecular Theory details and rate laws.




                                                                                        18
  Chemistry   Unit: 8


Module 3: DETAILED
INSTRUCTIONAL PATHWAY
                                                                          Teacher Notes:
                                                                          Differentiation / Scaffolding
DAY 15                                                                    & Common Misconceptions
Engage: Demonstrate the reaction of zinc with hydrochloric acid.
Students will work in groups to complete the brainstorming for the
inquiry lab (Activity8.7).
Let students struggle for a while and as you walk around gauge where
they are having difficulties.
The idea that the molecules must come in contact with each other
seems so obvious that they may look for something more
complicated.
Asking for student sketches of the molecules will help them see that if
the zinc is to bond with the chloride then the atom will need to be
close by.
 Remind students that particle arrangement differs based on state of
matter. You will probably have to help them try to sketch the acid as
a solution. With a good sketch at the particle level the students
should be better able to list the factors which they feel will increase
the rate of the reaction. You may need to help them with the concept
of concentration.
Crowding is an acceptable concept for now; however, later on you
will need to explain what 1M, 3M and 6M mean.
Discuss with students the features of a well designed experiment that
is intended to test if a given factor has the predicted effect.
Students may not have a good concept of rate so you will need to
review rate with them. You will also need to discuss that the rate can
be measured in two ways: How much reaction there is in a given
time or how much time it takes to get to the same point in a reaction.
Students will design how they will control the other factors and how
they will change the variable that they are testing.
 Suggest small quantities to use. The various tests that can be done
are as follows:

   1. Test 1M, 3M & 6M HCl with mossy zinc
   2. Test mossy zinc, powder zinc, and granule zinc with 3M HCl
   3. Test mossy zinc and 3M HCl at a cold temperature, at room
      temperature and at a hot temperature

                                                                                          19
They can measure how long it takes for all the bubbles to cease;
measure how much zinc has reacted after a given time; measure how
big a balloon is after a given time; or they can measure how long it
takes for a balloon to reach a certain size. Encourage creativity.

DAY 16 & 17
Explore: As a warm-up you may want students to interpret the
graphs on overheads 197 and 198.
These show the activation energy and how sometimes using a catalyst
can lower that activation energy.
Approve all lab procedures before students begin.
 Remind students that each step needs to be part of their procedure;
they can’t just write down that they are testing mossy zinc at three
different temperatures. They need to tell you how they are going to
complete the test including what the variable is, and how they are
keeping everything else constant such as the amount and
concentration of chemicals used. Encourage them to record all of
their observations.

Day 18 & 19
Explain/ Elaborate: Students will prepare overheads to summarize
their findings and to make presentations to the class.
As each group presents, ask students to take notes as their individual
lab reports should include an analysis of the different approaches
taken by each group.
Check for understanding throughout the investigation. Students
should prepare their own lab report.

Day 20

Evaluate: As a follow up ask students to complete worksheet 8.9

Day 21 Culminating Assessment

Day 22 Review

Day 23 Exam




                                                                         20
Name: __________________________ Date: _________ Period: ___
Activity 8.1
LAB: HOW BADLY WERE YOU CHEATED?

Pre- Lab Discussion: In early American communities sugar was a precious
commodity and a distributor might try to cheat his customers by adding
bicarbonate of soda or baking soda (NaHCO3) to “stretch” his product.

PROBLEM: You are an analytical chemist subpoenaed to testify in civil court on
behalf of the plaintiff (the distributors customers), to determine whether the
product that was sold is a pure substance or a mixture. You were given samples to
test and your task is to rank these from the most pure sugar to the least pure.

Materials: You will be given:
                  1) Three bags of white powder.
                  2) A beaker of vinegar.
                  3) A sample of pure sugar.
                  4) A sample of pure bicarbonate of soda.
 You need to develop a procedure to test for the impurity and be able to make a
comparison between the three samples.
You will:
 1) Describe in detail your procedure (what you did) and your results so that we
    can take the evidence to court and prosecute the cheaters.
 2) Develop a method which will allow you to say just how much more
    bicarbonate of soda is in one mixture compared to another. This may mean that
    you need to weigh out how much mixture you are using and use droppers to
    control how much vinegar you are using. Test tubes are provided so that you
    do not need to test large quantities. You do not want to waste your samples!
 3) Write an explanation justifying your results. Remember it should have a claim
    (what you think happened), evidence (data to answer how you know), and
    reasoning (what science about chemical reactions supports your claim so that it
    is reasonable and makes sense)
 4) Use the attached page to document ALL of your trials and data (evidence).
    You do not want the judge to throw the case out of court!




                                                                                21
Activity 8.1 continued

                                       Reaction with vinegar

Pure sugar


Pure bicarbonate of soda(NaHCO3)




Make a data chart to record your testing and observations.




What do you think happened during the reaction?


What do you know about the properties of each reactant?


Other than appearance, how do you know which powder is sugar and which one is
the sodium bicarbonate?


How does knowing this information help you solve the problem?




                                                                            22
Name: __________________________ Date: _________ Period: ___
Worksheet 8.1

Moles, Molecules, and Grams review

  1. How many grams are there in 2.3 x 1024 atoms of gold?




  2. Mow many grams are there in 9.4 x 1025 molecules of H2?




  3. How many molecules are there in 230 grams of CuCl2?




  4. How many grams are there in 7.4 x 1023 molecules of AgClO3?




  5. How many molecules are there in 2.3 grams of (NH4)2SO4?




   6. How many grams are there in 4.5 x 1022 molecules of Ba(NO3)2




                                                                     23
Name: __________________________ Date: _________ Period: ___
Activity 8.2
STOICHIOMETRY MOLE - MOLE

What information does the Chemical equation tell you?

BALANCE


    Fe                 O2                                  Fe2O3




            atoms           molecules                              molecules


            moles             moles                                 moles


              g                  g                                   g



Balance

___ MgCO3 (s) + ___ H3PO4 (aq) ----> ___ Mg3(PO4)2 (s) + ___ CO2 (g) + ___ H2O (l)

This tells us that:




                                                                                24
What if I had 6 moles of MgCO3
         Then how many moles of H3PO4 would I need? ___________
         How many moles of CO2 are produced?        ___________
         How many moles of Mg3(PO4)2 are produced? ___________

What if I had 1 mole of H3PO4 ,
 How many moles of Mg3(PO4)2 would be needed?        ___________
 How many moles of CO2 are produced?                 ___________
 How many moles of water are produced?               ___________

Balanced chemical equation lets you change mole A to mole B

Example: KClO3 -----> KCl +         O2


How many moles of oxygen will be produced when 0.234 moles of KClO3
decomposes?                 ______ to ________

1. Balance equation
2. Write in the given
3. Write in the? & unit




Example:

C2H6 + O2 -----> CO2 + H2O


How many moles of oxygen are needed to burn off 4.57 moles of C2H6?
                                      ________ to _________


1. Balance the equation
2. Write in the given
                                                                      25
3. Write in? & unit




    KOH      +   H3PO4 -------> K3PO4         +    H2O

How many moles of H3PO4 are needed to react with .42 moles of KOH?




Solid copper is added to silver nitrate solution to produce solid silver and copper
(II) nitrate solution. How many moles of silver will be formed if 0.55 moles of
copper is used?

Equation:



Problem:




                                                                                      26
Teacher Answer Key
Activity 8.2
STOICHIOMETRY MOLE - MOLE

What information does the Chemical equation tell you:

BALANCE


    4Fe                       3O2

                                                  2Fe2O3




               4          3                                         3 molecules
atoms                molecules
              23                   23                          23
x 6.02 x 10          x 6.02 x 10                 x 6.02 x 10


               4               3                          2 moles
moles                moles


4 mole x 55.8 g          3 mole x 32.0 g          2 mole x 160 g =
=              1     =                              1      1mole
1mole                     1             1mole                                g
                                          g
g
Balance

   3MgCO3 (s) + 2H3PO4 (aq) ----> Mg3(PO4)2 (s) + 3CO2 (g) + 3H2O (l)

This tells us that

3 moles MgCO3, when it reacts with 2 moles H3PO4, will produce 1 mole of
Mg3(PO4)2 , 3 moles of CO2, and 3 moles of water.

                                                                                  27
Name: __________________________ Date: _________ Period: ___
Worksheet 8.2: Homework

STOICHIOMETRY Mole - Mole ratio
Balance all chemical equations first.

1.     Na2SO3    +    HCl -----> NaCl        + H2O + SO2

How many moles of SO2 are produced when 2.4 moles of Na2SO3 are reacted with
excess acid?




2.   NaHCO3 -----> Na2O        +       CO2   +   H2O

How many moles of CO2 are produced when 0.63 moles of NaHCO3 decompose?




3. C3H8     + O2     ------> CO2   +     H2O

How many moles of oxygen are needed to burn off 1.4 moles of C3H8?




4.   MgCO3      +    HNO3 -----> Mg(NO3)2 +       CO2     + H2O

How many moles of nitric acid are needed to produce .745 moles of carbon
dioxide?

                                                                           28
5.   C2H6 + O2 -----> CO2 +         H2O

How many moles of oxygen are needed to burn off 0.064 moles of C2H6?




6. 0.435 moles of aluminum is treated with sulfuric acid to produce hydrogen gas
and aluminum sulfate. How many moles of hydrogen gas are produced?

Equation:


Problem:




7. Acetylene (C2H2) undergoes complete combustion with oxygen. How many
moles of oxygen are needed to burn off 6.23 moles of acetylene?

Equation:


Problem:


8. A barium chloride solution is combined with a solution of potassium
phosphate to produce a precipitate of barium phosphate and a solution of
potassium chloride. How many moles of barium phosphate are formed when
0.334 moles of barium chloride are reacted?

Equation:



Problem:

                                                                               29
Name: __________________________ Date: _________ Period: ___
ACTIVITY 8.3: Whole group Guided Practice

STOICHIOMETRY --- Mass - Mass Problems

Warm-up:
  1. Which of the following is a correct interpretation of the balanced chemical
     equation?

     a) 2 atoms of aluminum and 3 molecules of lead nitrate will produce 2
        molecules of aluminum nitrate and 3 atoms of lead.
     b) 2g of aluminum and 3 g of lead nitrate react to produce 2 g of aluminum
        nitrate and 3 g of lead.
     c) 2 moles of aluminum and 3 moles of lead nitrate react to produce 2 moles of
        aluminum nitrate and 3 moles of lead.


     2. If 3 moles of hydrochloric acid are consumed in the reaction below, how
        many moles of iron (III) chloride are produced?

            HCl + Fe2O3  Fe Cl3 + H2O



3.           Zn(s) + H3PO4 (aq)  Zn3(PO4)2 + H2(g)

Question: How many grams of phosphoric acid are needed to use up 8.3 g of zinc?

     i)     First balance the equation.
     ii)    What conversion is the question asking?
     iii)   First step is to change grams of zinc to moles of zinc. Set this up.


     iv)    Now you have moles of zinc, you need to change them to moles of
            H3PO4. Where do we get these numbers? Add this to step (iii)



     v)     Finally, the answer needed is grams of H3PO4. So how can we change
            moles of H3PO4 to grams of H3PO4?

                                                                                   30
Add this conversion to step(iv)



All the steps together:

grams of A            moles of A           moles of B             grams of B

           formula mass      balanced chemical          formula mass
            of A              equation                    of B




Example 1.
How many grams of oxygen will be formed when 3.86 g of KClO3 decompose?

   KClO3     ------> KCl + O2




1. How many grams of sodium hydroxide will be produced when 7.8 g of sodium
oxide is dissolved in water?

 Na2O       + H2O -----> NaOH




2. Heating an ore of antinomy, Sb2S3, in the presence of iron gives the element
antinomy, Sb, and iron(II) sulfide.
                                                                                  31
              Sb2S3(s)     +    Fe(s) ------> Sb(s)   +   FeS(s)

How many grams of antinomy are produced when 8.9 g of FeS are produced?




3.
        H3PO4 +          CaCO3 ----->   Ca3(PO4)2 + H2O +          CO2

How many grams of phosphoric acid react with excess calcium carbonate to
produce 6.34 g of Ca3(PO4)2?




Homework
  1. Given the following equation: 2 KClO3 ---> 2 KCl + 3 O2
     How many grams of O2 can be produced by letting 28.7 grams of KClO3
     react?

     2. Silver sulfide (Ag2S) is the common tarnish on silver objects. What weight
        of silver sulfide can be made from 4.23 g of hydrogen sulfide (H2S) obtained
        from 100 rotten eggs? The reaction and formation of silver sulfide is given
        below:
        Ag(s) + H2S(g) + O2(g) Ag2S(s) + H2O(l) (Equation must first be balanced.)

     3. A somewhat antiquated method for preparing chlorine gas involves heating
        hydrochloric acid with pyrolusite (manganese dioxide), a common
        manganese ore. How many kg of HCl react with 5.69 kg of manganese
        dioxide? (Hint: Make sure your units cancel and balance your equation)

        HCl(aq) + MnO2(s)  H2O(l) + MnCl2 (aq) + Cl2(g)




                                                                                  32
Name: __________________________ Date: _________ Period: ___
Worksheet 8.3 STOICHIOMETRY: Small Group Work
Chemistry

All Equations need to be balanced!

1. How many grams of lead (II) sulfate are formed when 6.8 g of aluminum
sulfate react with lead (II) chloride?

          Al2(SO4)3 + PbCl2 ------>       AlCl3 + PbSO4




2. Solid lithium hydroxide (LiOH) is used in spacecraft to remove the exhaled
carbon dioxide. How many grams of carbon dioxide can be absorbed by 1 gram of
LiOH?

          LiOH      +    CO2 ----> Li2CO3 +         H2O




3. How many grams of aluminum chloride will be produced when 92 g of
chlorine gas is bubbled over aluminum bromide?

    Cl2     +    AlBr3 ----->   AlCl3   + Br2



4. How many grams of copper will be produced when 40.0 g of aluminum is
added to a solution of copper (II) sulfate? The other product is aluminum sulfate.
(Remember you need a balanced chemical equation)



                                                                                 33
5. When octane (C8H18) is burned in oxygen, water and carbon dioxide are
produced. How many grams of water are produced when 320 g of octane is
burned?




6. What mass of barium chloride is needed to react completely with 46.8 g of
sodium phosphate? The products are barium phosphate and sodium chloride.




                                                                               34
Name: __________________________ Date: _________ Period: ___
Worksheet 8.4 STOICHIOMETRY- Mixed problems: Additional Practice
Problems.
Balance all Chemical Equations.

1. How many moles of oxygen are needed to burn off 6.0 g of C3H8?

             C3H8 +      O2 ----> CO2     + H2O




2. How many grams of sodium hydrogen carbonate are needed to produce 0.65
moles of carbon dioxide?

     NaHCO3 -----> Na2O       + CO2     + H2O




3. How many moles of hydrogen will be produced when 12.4 g of iron are heated
in water?

              Fe   +   H2O ------> Fe(OH)2 + H2




4.         B2H6 + O2 ----> B2O3 +          H2O

How many moles of oxygen are needed to use up 1.34 moles of B2H6?




                                                                            35
5. How many grams of CS2 will be produced when 5.8 g of S2Cl2 react with
carbon tetrachloride?

       S2Cl2     + CCl4 -----> CS2 +          Cl2




6. How many moles of hydrochloric acid are needed to react with 5.6 g of TiO2?

       TiO2 +      HCl ----> TiCl4 + H2O




7. How many moles of NO will be produced when 0.76 moles of NH3 are burned
in oxygen?

           NH3     +   O2 ----> NO       +    H2O




8. How many moles of hydrogen are produced when 14.7 g of aluminum react
with excess sulfuric acid? (the other product is aluminum sulfate).




                                                                                 36
Name: __________________________ Date: _________ Period: ___

Worksheet 8.5: Group Work Stoichiometry Review
EACH individual must submit his/her own work!

1.How many moles of ammonium sulfate can be made from the reaction of 30.0
mol of NH3 with H2SO4, according to the following equation:
                         2NH3 + H2SO4  (NH4)2SO4


2.Potassium permanganate and glycerin react explosively according to the
following equation:
            14KMnO4 + 4C3H5(OH)3  7K2CO3 + 7Mn2O3 + 5CO2 + 16H2O
How many moles of carbon dioxide can be produced from 4.44 mol of KMnO4?

3.In a space shuttle, the CO2 that the crew exhales is removed from the air by a
reaction within canisters of lithium hydroxide. On average, each astronaut exhales
about 20.0 mol of CO2 daily. What mass of water will be produced when this
amount reacts with LiOH? (The other product of the reaction is Li2CO3).



4.Water is sometimes removed from the products of a reaction by placing them in a
closed container with excess P4O10. Water is absorbed by the following reaction:
P4O10 + 6H2O  4H3PO4
If the P4O10 in the container absorbs 0.614 mol of water, what mass of H3PO4 is
produced?


5.A car battery produces electrical energy with the following chemical reaction:
Pb(s) + PbO2(s) + 2H2SO4 (aq)  2PbSO4(s) +2H2O (l) If the battery loses 0.34 kg
of lead in this reaction, how many moles of lead (II) sulfate are produced?



6.Joseph Priestley is credited with the discovery of oxygen. He produced O2 by
heating mercury (II) oxide, HgO, to decompose it into its elements. How many
moles of oxygen could Priestley have produced if he had decomposed 517.84 g of
mercury (II) oxide?



                                                                                37
7.What mass of sulfuric acid, H2SO4, is required to react with 1.27 g of potassium
hydroxide, KOH? The products of this reaction are potassium sulfate and water.



8.Lead (II) nitrate reacts with potassium iodide to produce lead (II) iodide and
potassium nitrate. If 1.23 mg of lead (II) nitrate are consumed, what is the mass of
the potassium nitrate produced?




                                                                                  38
Name: __________________________ Date: _________ Period: ___
Activity 8.4
DOES ADDING MORE REACTANT GIVE ME MORE PRODUCT?

1. Reaction of HCl and CaCO3
Add 25.0 mL of 3M HCl (0.075 moles) to each of three Erlenmeyer flasks. Then
weigh out 2.0 g (0.02 moles), 4.0 g (0.04 moles) and 6.0 g (0.06 moles) of CaCO3.
Add the powder to the three balloons. Attach the balloon to each of the flasks and
then shake the balloon so that the powder drops into the flask. Try to make sure
that all the powder is in the flask. Swirl the contents of the flask to make sure that
the chemicals have finished reacting. On the diagram below try to sketch the
relative sizes of the balloons and what you see in the flasks.




                  2.0 g                4.0 g               6.0 g


 2.0 g CaCO3 (0.02 moles) 4.0 g of CaCO3 (0.04 moles)   6.0 g of CaCO3 (0.06 moles)

25 mL of HCl (0.075moles) 25 mL of HCl (0.075moles)     25 ml of HCl (0.075moles)
Observations of           Observations of contents      Observations of contents
contents of flask.        of flask.                     of flask.




Did adding more of the calcium carbonate result in more products?


Answer this question and make sure that you refer to the evidence of the data.




                                                                                      39
  MACRO: For flask #3, describe what you saw at the end of the reaction and
  what it implied.




  NANO: Describe in words what is happening at the particle level in flask #3.




  SYMBOLIC:
  Draw circles to represent the atoms before and after the reaction in flask #3.
  Make sure that your representation is a true description of what happened.



               CaCO3
                                                     H2O             CO2           CaCl2
CaCO3
                         HCl

                                                             CaCl2
         HCl
                            HCl
                                                                                     H2O
  HCl            CaCO3                               CO2             CaCO3




                                                                                    40
Name: __________________________ Date: _________ Period: ___
Activity 8.5: Whole Group Discussion
  1. What did we learn from yesterday’s activity?




                     2.0 g               4.0 g       6.0 g

Having too much of one thing and not enough of another happens all the time.

2. For a peanut butter & jelly sandwich




How many sandwiches can I make?



What determined this?


3.
                        Number of          Used Up     Too much
                        capped bottles

5 bottles + 2 caps

5 bottles + 5 caps

5 bottles + 10 caps


                                                                          41
3. The Ford plant makes 4-wheel pick-up trucks. There are 1350 truck bodies
without wheels. There are 2500 wheels.

   a) How many finished trucks can be made?

   b) What is the combining ratio to make trucks?

   b) Which part is left over?


   d) How many excess parts are there?


The LIMITING REAGENT IS


The EXCESS REAGENT IS


A reaction can only produce as much as the limiting reagents will allow.


4. Consider the equation: SO2(g) + O2(g)  SO3(g)                =S        =O




What is the limiting reagent?              What is the excess reagent?


How many moles of SO3 were formed? What was left over?

5. Cu(s) + S(g)  Cu2S(s)           = Cu        =S




                                                                                42
What is the limiting reagent?              What is the excess reagent?

The amount of product formed depended on _________________________


6. This reaction is used to make steel.

               Fe2O3 (s) + H2 (g)          Fe (s) + H2O (g)

a) If 2 moles of Fe2O3 react with excess H2, _______ moles of Fe will be produced.

b) If 2 moles of Fe2O3 are reacted, ___ moles of H2 are needed to use it up.

c) If 2 moles of Fe2O3 are reacted with 3 moles of H2, will there be enough H2 to
use up all the Fe2O3? ____

What is the excess reagent? ______        What is the limiting reagent?______



7.    C2 H6 (g) + O2 (g)  CO2 (g) + H2O (g)

     a) 3 moles of C2H6 are burned in 7 moles of O2.

Look at the chemical equation:
If you have 2 moles of C2H6 you would need ______ moles of O2.
Is there enough O2 to react with 3 moles of C2H6?

Which is the limiting reagent?                 Which is the excess?

The limiting reagent decides how much product is formed.

When ______ moles of ________are used, how many moles of CO2 are produced?

When ______ moles of _______are used, ___moles of _____are needed.


So __________ moles of ___________ are left over.



                                                                                    43
8.          P + O2  P2O5

What if 4 moles of P combine with 6 moles of O2?

     i)       How many moles of O2 are needed to react with 4 moles of P?___

Do you have enough?

Which chemical is used up?

Which chemical is the limiting reagent?

Which chemical is left over?

     ii)      Use the limiting reagent to predict how much P2O5 is formed.


     iii)     How many moles of excess are left over?


     iv)      Draw circles to represent the atoms to show what is happening.




                                                                               44
Name: __________________________ Date: _________ Period: ___
Activity 8.6

Combine the solutions of sodium carbonate and calcium chloride in the quantities
indicated below in the 5 test tubes.
 Allow the solid to settle.
Measure the height that the solid reaches in the test tube and record.
Take a small amount of the liquid above the precipitate and add to the wells of a
spot plate in the same order as the test tubes.
Now add a few drops of sodium carbonate solution to each well and record your
observations.
Repeat, removing the liquid above the precipitate but this time test with the
calcium chloride solution.


Test tube          Vol. 0.2 M          Vol. 0.2 M         Height of
                   Na2CO3              CaCl2              precipitate

#1                 3.0 mL              12.0 mL

#2                 6.0 mL              9.0 mL

#3                 7.5 mL              7.5 mL

#4                 9.0 mL              6.0 mL

#5                 12.0 mL             3.0 mL



             above #1    above #2      above #3     Above #4     Above #5
Reaction     (yes or no)
with
Na2CO3

Reaction
with CaCl2



                                                                                45
RESULTS:

1. In which test tube did you find the largest amount of precipitate?


2. What information did the reactions of the liquid above the precipitate and the
   two reactants tell you? Be specific about each test tube.

Test Tube                                  Information
    1

    2

    3

    4

    5


3. Why do you think that one test tube obtained the highest yield?




4. Why did the other test tubes have smaller yields even though each test tube
   contained 15 mL of reactants?




5. What is the ratio of the volumes of the two reactants in the test tube with the
   highest yield? What do you think it represents?




                                                                                     46
6. MACRO: Explain what happened when you tested the solution above the
   precipitate in test tube #3. What did these results tell you about what was in
   that solution? Explain.



   NANO: Write a balanced chemical equation for the reaction.
   Compare the volume ratio of the two reactants used in test tube#3. Use these
   numbers to explain your results.




      SYMBOLIC: Sketch a test tube and write the chemicals present and where
      they are in the test tube.




                                                                                    47
Name: __________________________ Date: _________ Period: ___
Worksheet 8.6 Limiting Reagents:

1. An assembled bike consists of a frame, a seat and two wheels. If there are 50
frames, 60 seats and 90 wheels:

What is the limiting reagent? _____
How many assembled bikes can be made? _____

2. For the reaction below, balance the equation and then, for the molecules in the
box, decide what will be left after the reaction.

                   Al + Cl2  AlCl3

                    Cl               Al
     Al
                          Cl
                   Al
    Cl
                           Cl       Cl
          Cl
What is the limiting reagent?               What is the excess reagent?

How many moles of AlCl3 are produced?

Which reagent determined how much product can be made?


3. For the reaction below, balance the equation and then, for the molecules in the
box, decide what will be left after the reaction.

                         N2 +   H2  NH3

               H           N        N
N
                   H
N
                           H
                   H
          H                     H

What is the limiting reagent?             Which reagent is in excess?

How many moles of NH3 are produced?

                                                                                     48
Which reagent determined how much product could be made?




4. Balance P2O5 + H2O  H3PO4

2 moles of P2O5 are combined with 8 moles of H2O

i) Which is the limiting reagent?                 Which is in excess?

ii) Use the limiting reagent to predict how many moles of H3PO4 are formed?




5. Zn (s) + 2 HCl (aq)  ZnCl2 (aq) + H2 (g)

A 6.0 g piece of zinc was added ,using a balloon, to each of the flasks which
contained the amount of acid shown in the flask. The balloons inflated to the
approximate sizes shown. Identify the limiting reagent and the excess reagent in
each flask and then explain the sizes of the balloons.




              0.1 mol HCl           0.2 mol HCl             0.4 mol HCl




                                                                                   49
Name: __________________________ Date: _________ Period: ___
Worksheet 8.7 Limiting Reagents II

1. Balance    C2H2 + O2  CO2 + H2O

3 moles of C2H2 are burned in 5 moles of O2

Represent the molecules in the boxes below and determine how many molecules of
product will be formed.




i) Which is the limiting reagent?               Which is in excess?


ii) How many moles of H2O are formed?


2. Balance    Al + Cl2  AlCl3

4 moles of Al are burned in 7 moles of Cl2

i) Which is the limiting reagent?                Which is in excess?

ii) Use the limiting reagent to predict how many moles of AlCl3 are formed?




3. Balance Li3N      + H2O  NH3 +             LiOH

If 4 moles of Li3N react with 6 moles of H2O

i) Which is the limiting reagent?                Which is in excess?



ii) Use the limiting reagent to predict how many moles of NH3 are formed?
                                                                              50
4. In an experiment, different masses of sodium metal are reacted with a fixed
   mass of chlorine gas. The amount of sodium used and the amount of sodium
   chloride formed is shown on the graph below.
                  NaCl produced by reacting sodium with chlorine
           Mass of NaCl
           produced




                                                 Mass of Na in (g)
   a) Explain the general shape of the graph,




   b) Estimate the amount of chlorine used in the experiment.




5. How many grams of zinc phosphate are formed when 3.5 g of potassium
   phosphate reacts with zinc nitrate?

Zn(NO3)2 + K3PO4  KNO3 + Zn3(PO4)2




   ii)   What assumption did you need to make?


                                                                                 51
Name: __________________________ Date: _________ Period: ___
Worksheet 8.8: STOICHIOMETRY REVIEW

Remember: ALL equations must be balanced

1. In the balanced chemical equation what do the numbers in front of the
   chemicals tell us?


2.          C3H8 + O2  CO2 + H2O

How many moles of oxygen are needed to burn off 2.7 moles of C3H8?




3.          Pb(NO3)2 + K2CrO4 - PbCrO4 + KNO3


How many grams of lead chromate will be formed when 3.2 g of lead nitrate reacts
with excess potassium chromate?




4.           Na2CO3 + H3PO4  Na3PO4 + H2O + CO2

How many moles of acid are needed to use up 4.8 g of sodium carbonate?




5.         C2H2   + O2  CO2 + H2O

How many grams of C2H2 can be burned with 3.3 moles of oxygen?



                                                                              52
6.     Al + Cl2  AlCl3

3.0 moles of aluminum is combined with 3.0 moles of Cl2

     a) What is the limiting reagent?

     b) What reagent is in excess?

     c) How many moles of AlCl3 will be formed?

     d) How many moles of excess chemical will be left over?



7.            NaHCO3  Na2O + CO2 + H2O

How many moles of CO2 will be produced when 6.0 g of NaHCO3 decompose?




8. When zinc is added to excess nitric acid, hydrogen gas and zinc nitrate are
   formed. How many grams of zinc are needed to produce 0.67 moles of
   hydrogen gas?




        ii)     Why was it necessary to state that “excess acid” was used?




                                                                                 53
9.


         P2       +        Q2                   P3Q

      a) Write a balanced chemical equation for the reaction between P and Q.


c)




Which is the limiting reagent? Which is the excess reagent?



10.           C3H8 + O2  CO2 + H2O

2 moles of C3H8 are burned in 13 moles of oxygen

      a) Find the limiting reagent.

      b) How many moles of CO2 are formed?

      c) How many moles of excess chemical remain?




                                                                                54
Name: __________________________ Date: _________ Period: ___
Activity 8.7:
    HOW TO MAKE A REACTION HAPPEN FASTER OR GET MORE
                REACTION IN A GIVEN TIME

PURPOSE: You are to hypothesize what factors can help speed up a chemical
reaction. You will then test one of these hypotheses as a group and then share
information to the class. Each person will be responsible for writing their own
report.

The reaction to be studied:   Zinc metal reacting with hydrochloric acid

Balanced chemical equation:


What is happening during this reaction?


What needs to happen for this reaction to occur (at the atom level)?



Draw a sketch of the atoms/molecules to show what is happening?




What must occur for more reaction to happen in a given time (at the atom level)?


What form are the atoms/molecules of the reactants? What does this mean in
terms of the mobility of the particles?




What factors (at the chemical level) will make the reaction happen faster?


How can we test each variable?

                                                                                   55
How should you design an experiment to test a hypothesis?




What conditions of the experiment will you keep constant?




What are you trying to measure? What is your dependent variable? How can you
measure this?




How will you get a manageable reaction? What are you looking for?




Test quantities and give your decision.



Write out a detailed procedure for your teacher’s approval.
List the materials required and make a data chart.




Kinetics.
                                                                           56
MACRO: Using your experiment ,describe what you observed when you changed
the variable.




NANO: AT the atomic level explain how your variable changed the rate of the
experiment.




SYMBOLIC: Represent the atoms with circles and show how the atoms/molecules
will interact.




                                                                              57
PRESENTATION BY GROUP

Give the hypothesis for the variable that your group tested and explain the basis
of the hypothesis.
Describe what variables you kept constant and how you changed the variable that
you were testing
Describe how you decided to measure the rate of your reactions
Give the conditions for each experiment.
Give the results
Explain how your results do or do not support your hypothesis.


 Individual Lab Reports
1. Purpose: What was the learning goal of the lab?
2. Background: Summarize our pre- lab discussion and describe what is necessary
for a chemical reaction to happen and what will make the reaction happen faster.
3. Hypotheses: List the three factors which you think will increase the rate of a
reaction and why.
4. Statement: Give the hypothesis for the variable that you tested. Also list which
conditions were kept constant and how you decided which reaction was faster.
5. Procedure: Give a detailed description of what your group did.
6. Data: List observations and measurements that you made.
7. Conclusion: Do your results support your hypothesis? Why?
8. Results: Summarize the results for each hypothesis as given by each group.
9. Analysis: Comment on which were the most effective ways to measure the rate
of a reaction.
10. Experimental Error: Suggest any improvements which you would make to your
experiment based on the class experience.




                                                                                 58
Name: __________________________ Date: _________ Period: ___
Worksheet 8.9: What Do I Know About How Reactions Happen?

1. When you made oxygen you found that many substances burned more quickly
in pure oxygen rather than air. Explain.




2. Why do you think food is refrigerated in order to stop it spoiling?




2. Why do you think steel wool will burn but a piece of steel held in a Bunsen will
   not?




4. Magnesium ribbon will combine with oxygen in the air. Magnesium oxide is
   formed.

   a) Write a balanced chemical equation



   b) Draw a sketch of the atoms and the molecules. Make sure that you represent
      these particles accurately, based on their state of matter.




   c) Which oxygen atoms will be the ones that react with the magnesium?



5. Explain what effect increasing the temperature has on how fast a reaction
   occurs?
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6. a) What happens to the rate of a reaction as it progresses? Did you notice this
      during your experiments?



   b) Give an explanation. Think of the particles.




7. a) How is the 3M hydrochloric acid different from the 6M hydrochloric acid?




   b) Sketch some particles to show the difference.




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 Sample
Assessment




             61
     Name: __________________________ Date: _________ Period: ___

                          TEST: STOICHIOMETRY
Equations are balanced. Show all work. I suggest you write down your
conversion each time.

1. Complete the following. Make sure that you also write in the information that
   you will use for the conversions

grams of A                                                  grams of B




2. Li3N + 3H2O -----> NH3 +             3LiOH

If 4 moles of Li3N react with 6 moles of H2O,

   a)What is the limiting reagent ?             b) What is the excess reagent?

   c) How many moles of NH3 are made?


   d) How many moles of excess are left over?


3. How many moles of carbon are needed to react with 0.45 moles of silicon
dioxide?

              SiO2    +   3 C -----> SiC + 2CO




3. How many grams of aluminum carbonate are needed to produce 5.5 moles of
   carbon dioxide?

   Al2(CO3)3 + 3 H2SO4 -----> Al2 (SO4)3 + 3 H2O               + 3 CO2

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5. How many grams of zinc phosphate are formed when 3.5 g of potassium
   phosphate react with zinc nitrate?

     3 Zn(NO3)2       + 2 K3PO4 -----> 6 KNO3 +      Zn3(PO4)2




6. How many moles of oxygen are needed to burn off 18.7 g of C6H14?




7.    2Na2O2      +     2 H2O ---> O2 + 4 NaOH

How many grams of NaOH will be formed when 48.0 g of Na2O2 are burned in
excess oxygen?




8. What is the definition of a

LIMITING REAGENT?

EXCESS REAGENT?

Which reagent determines how much product is produced?


When will a reaction stop?


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9. Balance           H2 + O2 ---> H2O




                                                   complete

a) Which is the limiting reagent?         b) Which is the excess reagent?

c) How many molecules of water are produced?

d) How many moles of excess reagent are left?



10. 25.0 mL of hydrochloric acid were added to each of the flasks below. 2.0 g,
    6.0 g and 12.0 g of potassium carbonate was added to three balloons which
    were attached to the three flasks and then inverted so that the contents mixed
    with the acid. A lot of fizzing was observed and the balloons inflated. The
    relative sizes are shown below. Explain why balloon number three was not
    larger than balloon number two even though more potassium carbonate was
    used.




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  Chemistry   Unit:8


Unit 8 CULMINATING PROJECT
                                           Pacing: 1 Day
MANADATORY ASSESSMENT Unit 8

Have students revisit Activity 8.1.
Students are to log how they can now look at this lab differently than they originally did.
They are to quantitatively determine which sugar is the most pure and also determine
how pure the sugar is.
Allow students to struggle with this to see what kind of ideas they come up with.
Since this is an inquiry activity where students have to determine their own procedure,
you may need to remind them that this is the second time they are doing this lab, the
difference is that now they need to determine how to find a ratio of how much
bicarbonate is in each mixture when compared to each other.
Students may need guidance in finding the ratio between mixtures.
You may be surprised at how your students decide to figure out how much of a reaction
they are dealing with: some may use the number of drops added until the reaction stops;
others may determine how long, in seconds , the reaction continues when a constant
volume of vinegar is added, and others may determine how much mass was lost due to
the creation of a gas.
If you want quantitative results you need to specifically ask this of your students or they
may tend to base their results on which mixture creates a higher level of bubbles or
bubbled more rapidly.




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