1. Chemistry 12.2

2. Chemical Calculations
12.2
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.

3. Writing and Using Mole Ratios
12.2
Writing and Using Mole Ratios
Writing and Using Mole Ratios
How are mole ratios used in chemical calculations?

4. Writing and Using Mole Ratios
12.2
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.

5. Writing and Using Mole Ratios
12.2
Writing and Using Mole Ratios
Mole-Mole Calculations
A mole ratio is a conversion factor derived from the coefficients of a balanced chemical equation interpreted in terms of moles.

6. Writing and Using Mole Ratios
12.2
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.
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.

7. 12.2
Manufacturing plants produce ammonia by combining nitrogen with hydrogen. Ammonia is used in cleaning products, fertilizers, and in the manufacture of other chemicals.

8. 12.2

9. 12.2

10. 12.2

11. for Sample Problem 12.2
Problem Solving Solve Problem 12 with the help of an interactive guided tutorial.

12. Writing and Using Mole Ratios
12.2
Writing and Using Mole Ratios
Mass-Mass Calculations

13. 12.3
In this Hubble Space Telescope image, clouds of condensed ammonia are visible covering the surface of Saturn.

14. 12.3

15. 12.3

16. 12.3

17. for Sample Problem 12.3 `
Problem Solving Solve Problem 13 with the help of an interactive guided tutorial.

18. Other Stoichiometric Calculations
12.2
Other Stoichiometric Calculations
Other Stoichiometric Calculations
What is the general procedure for solving a stoichiometric problem?

19. Other Stoichiometric Calculations
12.2
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.

20. Other Stoichiometric Calculations
12.2
Other Stoichiometric Calculations
Solution Diagram
This general solution diagram indicates the steps necessary to solve a mass-mass stoichiometry problem: convert mass to moles, use the mole ratio, and then convert moles to mass. Inferring Is the given always a reactant?

21. Other Stoichiometric Calculations
12.2
Other Stoichiometric Calculations
Problem-Solving Approach
With your knowledge of conversion factors and this problem-solving approach, you can solve a variety of stoichiometric problems. Identifying What conversion factor is used to convert moles to representative particles?

22. Other Stoichiometric Calculations
Simulation 13
Strengthen your analytical skills by solving stoichiometric problems.

23. 12.4
The electrolysis of water causes it to decompose into hydrogen and oxygen.

24. 12.4

25. 12.4

26. 12.4

27. for Sample Problem 12.4
Problem Solving Solve Problem 15 with the help of an interactive guided tutorial.

28. 12.5

29. 12.5

30. 12.5

31. 12.5

32. for Sample Problem 12.5
Problem Solving Solve Problem 18 with the help of an interactive guided tutorial.

33. 12.6

34. 12.6

35. 12.6

36. 12.6

37. for Sample Problem 12.5
Problem-Solving Solve Problem 19 with the help of an interactive guided tutorial.

38. 12.2 Section Quiz.
12.2.

39. 12.2 Section Quiz. C3H8 + 5O2  3CO2 + 4H2O
1. 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

40. 12.2 Section 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

41. 12.2 Section 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

42. END OF SHOW