# Tentative Chapter Three Assignments and Schedule

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```					         Tentative Chapter Three Assignments and Schedule
Any and/or all problems will be collected each day and scored for correctness.

Date           Video Due      Book Section       Problems              Comments
One            1              3.1-3.2            12,14,16,18,20        Balancing Equations, Simple Types of Rxns.

Electrolysis demo. Rxn demos.

Read the caption for Figure 3.2, “The difference between a
subscript…and a coefficient”

Two                           3.2 cont.          names, formulas
and balanced
equations WS

Three                         3.3                22, 24 and in-class
quiz                  quiz on writing balanced reactions

Four           2              3.4                28,30, 34,36,38       Mole Inter-conversions

Five           3                                 LAB: Determining
the ratio of
reactants

Six                           3.5                39, 40, 46, 49        Empirical, Molecular Formulae, “what is a hydrate?”

Seven          4                                 LAB:
Determination of a
Chemical Formula

Eight                                             50, 51, 52           Combustion Analysis, continue lab

Nine           5              3.6                2,4,5,6, 56,57,58     Stoichiometry

Ten            6                                 60,62,63,66           Finish lab

Eleven                        3.7                68,71,72,74 (“d” is   Limiting Reactants
optional), 76

Twelve                        Review Ch3         93, 99 and take
home quiz
problems assigned

Thirteen                      Ch3 Test           Take home quiz
problems due
Names, Formulas and Balanced Equations Worksheet

Name:                                                Write the formula:
W2O5                                                 Cobalt III peroxide
Ni(CH3COO)2                                          Mercury I sulfite
C2H6                                                 Dinitrogen hexafluoride
HBr                                                  Propane
H2Se                                                 Perbromic acid
N2F5                                                 Silver nitrate
KMnO4                                                Hyposulfurous acid
C4H10                                                Nitrogen trioxide
Mo(SO4)2                                             Zinc phosphate
HClO                                                 Barium nitride
Ru(ClO2)4                                            Hexane
P4O8                                                 Arsenic acid
SO2                                                  Fluorous acid
CO2                                                  Octane
PbS2                                                 Lithium dichromate
SnC2O4                                               Iron II hydrogen carbonate
V(IO3)5                                              Uranium VI fluoride
Cd(BrO)2                                             Sulfurous acid

Write the complete balanced chemical equation.

1) Gold combines with sulfur under the correct conditions to produce gold I sulfide.

2) Butane burns in oxygen to produce carbon dioxide and another wet product.

3) Calcium sulfate combines with nickel II phosphide to produce calcium phosphide and nickel II
sulfate.

4) Aluminum perchlorate reacts with titanium IV sulfate to produce aluminum sulfate and titanium
IV perchlorate.

5) Elemental strontium replaces hydrogen in water producing an explosive gas and the base
strontium hydroxide.
3.1 Chemical Equations

2H2(g) + O2(g)       2H2O(l)

(s)
(l)
(g)
(aq)

How many atoms of Mg, O and H are represented by 3Mg(OH) 2?

Law of Conservation of Matter:

Na(s) +     H2O(l)  NaOH(aq) + H2(g)

Another example:
Fe + O2          Fe2O3

3.2 Some Simple Patters of Chemical Reactivity

Combination (sometimes called synthesis)

Decomposition

Combustion in air
3.3 Formula Weights

Formula Weight
Molecular Weight
a.k.a. Formula Mass, Molecular Mass

H2SO4

C6H12O6

Percentage Composition

Calculate the percentage of carbon, hydrogen and oxygen (by mass) in C12H22O11.

3.4 Avogadro’s Number and the Mole

Calculate the number of H atoms in 0.350 mol of C 6H12O6

How many oxygen atoms are in 0.25 mol of Ca(NO3)2.
Molar Mass or Molar Weight
12
C
Magnesium-24
197
Au

Notice that when we are dealing with a particular isotope of an element, we use the mass of that isotope;
otherwise we use the atomic weight (the average atomic mass) of the element.

The mass in grams of one mole of a substance is called the molar mass.

What is the mass in grams of 1.00 mol of C6H12O6 (a.k.a. glucose)?

Calculate the number of moles of C6H12O6 in 45.0g of glucose (C6H12O6).

Calculate the number of C6H12O6 molecules in the 45.0g sample of glucose (C6H12O6).
.

Interconverting between mass   moles   particles:

Determine the number of
a) moles of glucose (C6H12O6) and
b) oxygen atoms
in 360.0g of glucose.
Determine the number of
a) moles of CO2(g) and
b) grams of carbon dioxide gas
in 1.505 x 1023 molecules of CO2(g).

3.5 Empirical Formulas from Analyses

Ascorbic acid (vitamin C) contains 40.92% C, 4.85% H and 54.50% O by mass. What is the empirical
formula of ascorbic acid?
Mesitylene, a hydrocarbon that occurs in small amounts in crude oil, has an empirical formula of C 3H4. the
experimentally determined molecular weight of this substance is 121 amu. What is the molecular formula
of mesitylene?

Combo problem:
Ethylene glycol, the substance used in automobile antifreeze, is composed of 38.7% C, 9.7% H and
51.6%O by mass. Its molar mass is 62.1 g/mol.
a) What is the empirical formula of ethylene glycol?
b) What is its molecular formula?
Combustion Analysis

Isopropyl alcohol, a substance sold as rubbing alcohol, is composed of C, H and O. combustion of 0.255g
of isopropyl alcohol produces 0.561g of CO2 and 0.306g of H2O. Determine the empirical formula of
isopropyl alcohol.
Another combustion analysis problem:
Caproic acid, which is responsible for the foul odor of dirty socks, is composed of C, H and O atoms.
Combustion of a 0.225g sample of this compound produces 0.512g CO 2 and 0.209g H2O.
a) What is the empirical formula of caproic acid?
b) Caproic acid has a molar mass of 116g/mol. What is its molecular formula?
3.6 Quantitative Information from Balanced Equations

3H2 + N2  2NH3

Coefficients in a chemical equation represent the relative numbers of molecules (and therefore moles)
involved in a reaction….which can be converted to mass.

How many grams of water are produced in the oxidation of 80.0g of glucose (C6H12O6)? The balanced
chemical equation is below.

C6H12O6 +     6O2  6CO2        +   6H2O

Solid lithium hydroxide is used in space vehicles to remove exhaled carbon dioxide. The lithium hydroxide
reacts with gaseous carbon dioxide to form solid lithium carbonate and liquid water. How many grams of
carbon dioxide can be absorbed by 1.00g of lithium hydroxide?
3.7 Limiting Reactants

Manufacture of cars….

The limiting reactant or limiting reagent:

How many moles of NH3 can be formed from 3.0mol N2 and 6.0mol of H2? (note, example of using an
“i.c.e.” table).

The balanced chemical equation:
3H2 + N2  2NH3
Consider the reaction:
2Al + 3Cl2  2AlCl3
A mixture of 54.0g of Al and 142.0g of Cl2 are allowed to react in an enclosed vessel.
a) which is the limiting reactant?
b) how many moles of AlCl3 are formed?
c) how many moles of excess reactant remain at the end of the reaction?
A second limiter example:
A 55.8g sample of pure iron is submerged in a solution containing 338.0g of silver nitrate. Fe(NO 3)3 and
solid silver are the products.
a) write the balanced chemical reaction.
b) determine the limiting reactant
c) determine the moles of each product produced
d) determine the mass of excess reactant remaining.
Theoretical Yields
The quantity of product that is calculated to form when all of the limiting reactant reacts is called the
theoretical yield. The amount of product actually obtained in a reaction is called the actual yield.

Percent yield =

In the last problem, two moles of silver were theoretically produced.
a) calculate the mass of silver that would theoretically be produced.
b) If 107.8g of silver are actually produced, calculate the percentage yield.

In a second, new, chemical reaction, the actual yield of silver was 75.0%. How many grams of silver were
actually produced?
Here is the list of "for sure" do problems:

mixed (visualizing concepts):
2,4,5,6,

balance equations/types rxns:
12,14,16,18,20,

formula mass and % comp:
22(only some),24 (usually takes longer to do),

mole (I like some of the ones that make them find the moles of
particular elements in a molecule: e.g., 38d), but many of these
problems have several parts...so they take awhile:
28,30,34,36,38,40,

empirical/molecular formulas:
44,46(only one or two of them),48,50,

general stoich probs:
56,58,60,62,66,

limiter probs:
68,71,72,74 (probably not "d"),76

Here is a list of maybe do's and extras:
11,13,15,22(more if needed),46 (the rest of the problem if needed),

Here is a list of quiz problems (partner, in-class, take-home or just
"put them on the ch3 quiz" problems):
87,93 (if need more stoich),99 (if need more limiter), 107 (I usually
give this one as a partner quiz...death by cyanide problem (kids like
the name, but then they find it hard), but good review of dim analysis
with stoich and some percentage stuff)

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