Download Unit 7 Review Answers

Chemistry
Unit 7 Review Answers
1-9 refer to the following chemical reaction shown by the skeletal equation: H 2(g) + O2(g) = H2O(g)
___1. How many moles of hydrogen are required to make 5 moles of water?
A. 2.5 B. 5 C. 10 D. 20 E. 40
___2. How many grams of oxygen are required to produce 20g of water? Assume excess hydrogen.
A. 28.8g B. 35.5g C. 8.9g D. 1.1g E. 17.7g
___3. How many liters of hydrogen gas are required to react with 20L of oxygen gas?
A. 10L B. 20L C. 40L D. 32L E. 16L
___4. How many molecules of H2 are required to react with 20g of O2?
A. 1.5X1023 B. 3.75X1023 C. 7.5X023 D. 2.5 E. 5
___5. How many grams of H2 are required to react with 30L of oxygen gas?
A. 2.7g B. 5.4g C. 10.8g D. 60 E. 15
___6. How many grams of H2O can be produced from 20g O2 and 3g H2?
A. 11.25g B. 27g C. 22.5g D. 33g E. 13.5g
___7. What is the percent yield of water if stoichiometry predicts 10g will be produced and 3.5g are
recovered in a reaction?
A. .35% B. 3.5% C. 35% D. 28.6% E. 2.86%
___8. What is the percent yield if 5g of water are recovered when 10g of H 2 are reacted with 100g of O2?
A. 5.5% B. .05% C. 10% D. 17.8% E. 8.9%
___9. How much of what reactant is left over from problem 8?
A. 20g O2 B. All reactants are used up C. 1.88g H2 D. .94g H2 E. 10g O2
10-15 refer to the following reaction shown by the skeletal equation H3PO4 + Ca(OH)2 = H2O + Ca3(PO4)2
___10. How many grams of water will be produced from 10g H 3PO4?
A. 22g B. 5.5g C. 11g D. 1.8g E. .6g
___11. How many grams of calcium phosphate will be produced from 10g calcium hydroxide?
A. 42 B. 7g C. 28g D. 4.7g E. 14g
___12. How many grams of water and calcium phosphate will be produced from 10g calcium hydroxide
and 10g phosphoric acid?
A. 4.9g H2O and 14g Ca3(PO4)2 B. 5.5g H2O and 15.8g Ca3(PO4)2 C. 4.9g H2O and 15.8g Ca3(PO4)2 D. 5.5g
H2O and 14g Ca3(PO4)2
___13. What is the percent yield when 20g of calcium phosphate is made from 50g H 3PO4 and excess
calcium hydroxide?
A. 50% B. 12.5% C. 25% D. 6.25% E. 75%
___14. Which makes more water, 10g of H3PO4 or 15g Ca(OH)2?
A. Both make the same amount B. 15g calcium hydroxide C. 10g phosphoric acid
___15. How many grams of Ca(OH)2 are required to react with 25g H3PO4?
A. 28g B. 12.6g C. 18,9g D. 14g E. 25.2g
16-24 refer to the following chemical reaction shown by the skeletal equation: H 2(g) + N2(g) = NH3(g)
___16. How many moles of hydrogen are required to make 10 moles of ammonia?
A. 15 B. 5 C. 10 D. 20 E. 40
___17. How many grams of nitrogen are required to produce 10g of ammonia? Assume excess hydrogen.
A. 8.2g B. 16.4g C. 4.1g D. 1.1g E. 28.8g
___18. How many liters of hydrogen gas are required to react with 10L of nitrogen gas?
A. 30L B. 10L C. 40L D. 20L E. 60L
___19. How many molecules of H2 are required to react with 10g of N2?
A. 6.45 X1023 B. 2.15X1023
___20. How many grams of H2 are required to react with 10L of nitrogen gas?
A. 5.4g B. 2.7g C. 10.8g D. 1.3g E. 15
___21. How many grams of NH3 can be produced from 10g N2 and 3g H2?
A. 12.1g B. 6g C. 24.2g
___22. What is the percent yield of ammonia if stoichiometry predicts 10g will be produced and 2.5g are
recovered in a reaction?
A. 25% B. 2.5% C. .25% D. 40% E. 4%
___23. What is the percent yield if 5g of ammonia are recovered when 10g of H 2 are reacted with 100g of
N2?
A. 8.8% B. .08% C. 10% D. 17.6% E. 11.2%
___24. How much of what reactant is left over from problem 8?
A. 53.3g N2 B. All reactants are used up C. 1g H2
25-29 refer to the following reaction shown by the skeletal equation H 2SO4 + Ca(OH)2 = H2O + CaSO4
___25. How many grams of water will be produced from 10g H2SO4?
A.
3.7g
B. 18.5g C. 9.25g
___26. How many grams of calcium sulfate will be produced from 10g calcium hydroxide?
A. 18.4 B. 9.2g C. 36.8g
___27. How many grams of water and calcium sulfate will be produced from 20g calcium hydroxide and
20g sulfuric acid?
A. 7.3g H2O and 24.4g CaSO4 B. 9.73g H2O and 36.8g CaSO4
___28. Which makes more water, 20g of H2SO4 or 30g Ca(OH)2?
A. 30g calcium hydroxide B. Both make the same amount C. 20g sulfuric acid
___29. How many grams of Ca(OH)2 are required to react with 25g H2SO4?
A. 18.9g B. 9.4g C. 37.8