Chemistry You Need to Know - PowerPoint

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					Section 1.3—Designing Your
                 Own Labs
Designing Labs
 When we DESIGN a lab it is not giving a set
  “scientific method”…rather it is helping you to
  stay focused on the goal when designing a lab.
 A Lab Design gives you a plan of attack, but you
  can adjust it as you need for various labs
Identify the purpose, problem, question
 If variables are appropriate (relationship or effect
  lab), identify them in the problem
   Example of a purpose: To determine the effect of
    temperature on pressure
 If variables are not appropriate, be as
  descriptive as possible
   Example of a question: What is the concentration of a
    saturated NaCl solution at room temperature?
 You can phrase it as a purpose or question
 You should also identify any important constants
Gather Background Information
 The background information section is where
  you combine all the different concepts you need
  to know in order to solve your problem or
  answer your question (to form your hypothesis)
 The background information section might
  contain:
  Definitions
  Known relationships
  Equations
Write a hypothesis
 Write a hypothesis only when appropriate—only
  in relationship or effect labs
 After looking at all your background information,
  make a hypothesis (prediction with explanation
  for why you think so)
Set-up the Results/Calculations section
 Now jump to the results and conclusion sections.
  We will write any equations that you will need to
  solve your problem or answer your questions.
 You won’t have numbers to plug in, but you can
  set up the equations/calculations now. 
Set-up the Data Table
 Go through the calculations you set up and make a data
  table that asks for each quantity you’ll need
 Remember that some measurements must be taken
  indirectly & you will need to take that into account:
   For example, you can’t put a chemical directly on the
     balance, so you’ll need the mass of the container
     (beaker or weighing dish) and then the mass of the
     container & chemical in your data table
 Your data table should not contain any calculated values
  (even just subtracting out the mass of the beaker)…only
  those you will actually measure with an instrument!
Write your Procedure
 Procedures should be:
    Clear, Concise, Numbered list of steps
    Repeatable by someone of your same level of
     experience/education
 Go through your data table and write a procedure
  step to measure each thing asked for in your data
  table.
 If the data table includes masses or volumes of
  chemicals, give an approximate amount in the
  procedure
    Example: Add approximately 2 g of NaCl to the beaker.
     Find exact mass & record.
Write your Materials List

 Go through your procedure and make a list of
  each piece of equipment and chemical that
  you’ll need
 Be sure to include how many of each type of
  equipment and what approximate quantity of
  chemical
  In the materials you can just say water – not 250
   mL of water
Write your Safety Concerns

 Go through your procedure & materials list
  and specify any safety concerns.
 Possibilities include:
  Wear goggles (anytime you use glass or chemicals)
  Use caution with glassware
  Use caution with hot glassware or hot chemicals
  Any cautions specific to a chemical you’re using
   (your teacher will tell you these)
  Report any spills, breaks or incidents to your
   teacher immediately
  Wear aprons or gloves, if necessary
Now you’re ready to do your lab!

 Begin performing your lab (after your teacher
  checks it for safety, if necessary)
 If you need to make changes to your
  procedure at any time (you realize it’s not
  quite right)…that’s OK
  Just make sure you change the written procedure
   as well so that when you’re done, the written report
   reflects what you actually did
 Record your data in the data table
 Complete the calculations you’ve set up
Write your Conclusion Paragraph

 Restate the purpose
 Completely answer the purpose with your
  results
 Address any earlier hypothesis…does your
  evidence support or not support it?
  If it does not support the hypothesis, propose a new
   hypothesis
 Suggest possible sources of error
  “human error” is not specific enough & “Calculations”
   doesn’t count

				
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