1. Basic Stoichiometry-student 1 .docx - Date Assigned: ...

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Basic Stoichiometry
How do chemists calculate quantities of reactants and products in chemical reactions?
Why?
One of the most important tasks for chemists is to be able predict not only the formulas
of reactants and products in chemical reactions, but also the quantities of reactant and
products. For example, if a chemist for a pharmaceutical company needs to produce a
specific amount of a medication from a chemical reaction, they are going to need to
know how much of the reactants to start with. Chemists use the process of
stoichiometry to solve these kinds of problems.
Model 1
2A + 3B  5C + 4D
Molar Ratio
2 mol A produces 5 mol C
3 mol B produces 4 mol D
2 mol A reacts with 3 mol B
1. What do the coefficients of a balanced equation represent?
2. Write three other molar ratios from the equation in Model 1.
3. Now for the three molar ratios you wrote in question #2, write each molar ratio as a
conversion factor.
(ex: 2 mol A = 5 mol C)
4. Write a definition for the term molar ratio
5. If 6 mol A are reacted, how many mol D are formed? Explain as a group how you
calculated this answer and show your work using dimensional analysis.
.

Model 2
2A + 3B  5C + 4D
If 3 mol A react, how many mol C are produced?
3 mol A x 5 mol C = 7.5 mol C
2 mol A
6. If 21.0 mol A are reacted, how many mol C are produced? Using dimensional
analysis, show how you calculated your answer.
7. If 21.0 mol B are reacted, how many mol A must have been consumed?
8. If 0.013 mol D are produced, how many mol C must also be produced?
9. Discuss as a group and define stoichiometry in your own terms.