STOICHIOMETRY

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STOICHIOMETRY
STOICHIOMETRY
How much do I need? How much can I get?
A Comparison of SCH4C and SCH3U Janine Passi HS
Chemistry
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Overview

• Introduction
• Our First Roadblocks
• Looking at the Expectations/Curriculum
• Three Lesson Sequence Including
• Introduction
• Even More Roadblocks
• Laboratory Exercise
• Assessment Evaluation
• Societal Application
• Resources

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Classic Analogies
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1

2
How many of each ingredient do I need to make 2
salads?
4
You multiply everything by 2 of course!


2
4
2
2
5

1
Whats the ratio of tires to steering wheel to
car?
411
If I only had 11 tires, how many complete cars
could I make?
2 with 3 tires left over
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ROADBLOCK 1

• Part a) Stoichiometry is too hard and Ill never
  be able to figure it out!
• Part b) Stoichiometry will never apply to
  anything in my life!

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ROADBLOCK2

• In order to go from 1 salad to 2 salads, and from
  1 to 3 cars we used a conversion factor
• In Stiochiometry the conversion factor is usually
  referred to as the molar ratio

Who me?
They are the SAME THING!!
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ROADBLOCK3

• How come if the mole ratio does not equal the
  mass ratio?
• Check out McGraw Hill Resource

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Simplified Expectation Comparison
Problem solving
Double Bubble Map
SIS
complexity
application
Vocab.
SCH4C
SCH3U
yield
limiting reagent
mole
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A Closer Look

• SCH 3U vs. SCH4C
• 1 QCV.02/.03 vs. QAV.02/.03
• 2 QC2.01 vs. QA2.01
• 3 QC3.01 vs. QA3.01/.03

p. 3 in outline
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Curriculum Placement

• Typically this is the 2nd unit.
• Unit 1 - Matter Qualitative Analysis
• Unit 2 - Chemical Calculations (Quantitative)
• Stoichiometry comes after the mole, percent
  composition etc. the last topic of the
  unit..arghh!

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Lesson 1

• What is stoichiomtry? Everyday life examples
• How to approach a stoichiometry problem.
• Consistently
• Rules
• Lots of Practice
• Highlighting Roadblocks

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Lesson 2

• Review from yesterday
• Introduce Concept of Percent Yield
• Demonstration of Percent Yield Experimental Data
• Begin Own Experiment (so it has time to dry over
  night)

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Lesson3

• Finish off Percent Yield in Class
• Societal Applications/Importance
• More Problem Solving, in preparation for the quiz

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ROADBLOCK 4

• Theoretical vs. Actual?
• Which one goes on top?
• How can I get an actual yield greater than the
  theoretical yield?

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Stoichiometry Problem A 4 Step Process

1. Write the balanced chemical equation for the
   reaction. (RED)
2. Calculate the number of moles of known quantity,
   using the molar mass (GREEN)
3. Using the molar ratio, determine the number of
   moles of the unknown quantity (YELLOW)
4. Convert the of moles to grams using the molar
   mass (PURPLE)

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Applications

• Cooking - Recipes
• Industry - pharmaceuticals, dyes, mineral
  extraction
• Environment - recycling

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Resources

• Tom Stretton
• Kiwi NZ
• Nelson 12 College, 11 Chemistry Teacher Resources