1. DRILL
Besides mass what is conserved during a chemical reaction?

2. OBJECTIVE The student will be able to:
Explore Stoichiometric equations in order to calculate quantities from balanced equations using units of moles, mass, and volumes of gases at STP.

3. SAT/HSA Enrichment
175.6g of NH3 gas is stored at STP. The volume of the gas at those conditions is…
10.32 liters
22.40 liters
175.6 liters
231.4 liters
3933 liters

4. Chemical Calculations
How to covert from one unit to another?

5. Chemical Calculations
The effectiveness of car’s air bags is based on the rapid conversion of a small mass of sodium azide into a large volume of gas. The entire reaction occurs in less than a second. You will learn how to use a balanced chemical equation to calculate the amount of product formed in a chemical reaction.

6. Writing and Using Mole Ratios
In chemical calculations, mole ratios are used to convert between moles of reactant and moles of product, between moles of reactants, or between moles of products.

7. Mole-Mole Calculations
A mole ratio is a conversion factor derived from the coefficients of a balanced chemical equation interpreted in terms of moles.

8. Writing and Using Mole Ratios
To determine the number of moles in a sample of a compound, first measure the mass of the sample. Then use the molar mass to calculate the number of moles in that mass.

9. SAMPLE PROBLEM

10. SAMPLE PROBLEM

11. SAMPLE PROBLEM

12. Mass-Mass Calculations

13. Other Stoichiometric Calculations
In a typical stoichiometric problem, the given quantity is first converted to moles.
Then the mole ratio from the balanced equation is used to calculate the number of moles of the wanted substance.
Finally, the moles are converted to any other unit of measurement related to the unit mole, as the problem requires.

14. Solution Diagram

15. Problem-Solving Approach

16. SAMPLE PROBLEM 2

17. SAMPLE PROBLEM 2

18. SAMPLE PROBLEM 2

19. SHORT QUIZ
How many moles of water are produced when 2.5 mol of O2 react according to the following equation?
C3H8 + 5O2  3CO2 + 4H2O
2.0
2.5
3.0
4.0

20. SHORT QUIZ
2. Nitrogen gas reacts with hydrogen gas to produce ammonia gas. N2(g) + 3H2(g)  2NH3(g) What volume of H2 is required to react with 3.00 L of N2, and what volume of NH3 is produced at 200°C?
volume of H2 = 9.00 L, volume of NH3 = 6.00 L
volume of H2 = 3.00 L, volume of NH3 = 3.00 L
volume of H2 = 3.00 L, volume of NH3 = 6.00 L
volume of H2 = 1.00 L, volume of NH3 = 1.50 L

21. SHORT QUIZ
3.Automotive airbags inflate when sodium azide, NaN3, rapidly decomposes to its component elements via this reaction: 2NaN3  2Na + 3N2. How many grams of sodium azide are required to form 5.00 g of nitrogen gas?
11.61 g
17.41 g
7.74 g
1.36 g

22. Quantitative Analysis
Purpose:
To determine the values for the coefficients used in a balanced chemical equation.
Complete Day 2 of the Quantitative Analysis Lab.
25 MIN

23. Summary Did we accomplish the objective?
Why is it important to balance an equation before calculating a Stoichiometric calculation?
What does the Coefficient tell you about an equation?
What are Coefficients used for in an equation?
How can you convert from one molecule to another?