Chemistry 100 Sample Exam 2

CHEMISTRY 100        SAMPLE EXAM 2        10-1-02
1. The formula for magnesium nitride is
     a. MgN.          b. Mg₃Ni.          c. Mg₂N₃.          d. Mg₃N₂.
2. What is the name of the compound whose formula is, K₂SO₄?
     a. Potassium sulfite      b. Potassium sulfate      c. Potassium sulfide      d. Dipotassium sulfate
3. The name of the compound CuO is
     a. copper oxide.      b. copper(II) oxide.      c. copper(I) oxide.      d. copper monoxide.
4. The name of the compound N₂O₄ is
     a. Nitrogen oxide.           b. Nitrogen(IV) oxide.
     c. Nitrogen tetroxide.      d. Dinitrogen tetroxide.
5. What is the correct name of SF₆?
     a. sulfur fluoride      b. sulfur heptafluoride      c. sulfur hexafluoride      d. sulfur hexafluorite
6. Calculate he formula weight of sodium thiosulfate, Na₂S₂O₃.
     a. 158.12 g/mol       b. 188.15 g/mol        c. 134.38 g/mol        d. 273.03 g/mol
7. What is the formula weight of calcium carbonate, CaCO₃?
     a. 188.11 g/mol         b. 175.33 g/mol            c. 201.32 g/mol         d. 100.09 g/mol
8. What is the mass in grams of 12.00 mol of sodium hydroxide?
    a. 240.0 g         b. 480 g         c. 360.0 g         d. 500.0 g
9. What is the mass of 0.750 moles of Al₂(SO₄)₃?
     a. 257. g         b. 154. g         c. 650. g         d. 332. g
10. How many moles are in 100.0 g CO₂?
     a. 2.899 mol         b. 2.326 mol         c. 2.737 mol         d. 2.272 mol
11. How many moles of boron are 100.00 g of magnesium borate, Mg(BO₂)₂?
      (Formula weight of Mg(BO₂)₂ = 109.93 g/mol)
     a. 0.9097 mol         b. 1.819 mol         c. 1.9932 mol         d. 0.7822 mol
12. A 1.000 mol sample of Mg(ClO₄)₂ contains
     a. 6.022 x 10²³ magnesium atoms.         b. 6.022 x 10²³ perchlorate ions (ClO₄^-1).
     c. 6.022 x 10²³ chlorine atoms.             d. 8 oxygen atoms.
13. Calculate the number of molecules in 1.00 gram of water.
     a. 6.02 x 10²³ molecules         b. 4.76 x 10²³ molecules
     c. 2.14 x 10²¹ molecules         d. 3.34 x 10²² molecules
14. How many grams of carbon are in 1.000 g of isopropyl alcohol, C₃H₈O?
     a. 0.5994 g         b. 14.22 g         c. 0.1133 g         d. 0.1855 g
15. What is the percent mass of oxygen in NaMnO₄?    (FW NaMnO₄ = 141.93 g/mol)
     a. 45.09%         b. 43.21%         c. 40.11%         d. 39.03%
16. Which of the following contains the LARGEST percent mass of carbon?
     a. CH₄             b. C₂H₆             c. C₃H₈             d. C₄H₁₀
17. What is the percent oxygen in calcium thiosulfate (CaS₂O₃)?
       The formula weight of calcium thiosulfate is 152.22 g/mol.
     a. 23.0%         b. 31.5%         c. 39.3%         d. 43.5%
18. Which of the following has the smallest percent oxygen by mass?
     a. SO₂         b. CO₂         c. NO₂
19. Upon combustion, a 5.645 g sample of an organic compound gave 19.083 g of CO₂;
       the percent by mass of carbon in the compound is
     a. 27.29 percent.          b. 29.58 percent.          c. 52.08 percent.          d. 92.25 percent.
20. Which of the following has the largest empirical weight?
     a. C₉H₁₂         b. C₆H₁₄         c. C₅H₁₂         d. C₇H₁₄
21. The composition of a certain compound is 67.2 percent Xe and 32.8 percent O;
       its empirical formula is
     a. XeO.          b. XeO₂.          c. XeO₄.          d. XeO₆.
22. Which one of the following reactions (equations) is balanced?
     a. C₂H₅OH + O₂ ---> H₂O + CO₂
     b. C₂H₅OH + 3 O₂ ---> 3 H₂O + 2 CO₂
     c. C₂H₅OH + O₂ ---> 3 H₂O + 2 CO₂
     d. 2 C₂H₅OH + 7 O₂ ---> 6 H₂O + 4 CO₂
23. Aluminum is produced from the oxide according to the following equation:
           Al₂O₃(s) --->     Al(s) +     O₂(g).
      When this equation is balanced, the coefficient of the aluminum is
     a. 1.          b. 2.          c. 4.          d. 6.
24. What is the sum of the coefficients in the balanced equation?
           KClO₃ +       C₁₂H₂₂O₁₁ --->         KCl +        CO₂ +        H₂O
     a. 39         b. 40         c. 42         d. 45
25. What is the coefficient of the NH₃ when the following equation is balanced?
         NH₃ +   Cl₂ --->    N₂H₄ +   NH₄Cl
     a. 1         b. 2         c. 3         d. 4
26. What is the sum of the coefficients for the combustion of C₃H₆?
     a. 23         b. 18         c. 25         d. 19
27. The reaction N₂(g) + 2 O₂(g) ---> 2 NO₂(g) indicates that
     a. one atom of nitrogen reacts with two atoms of oxygen.
     b. one molecule of nitrogen reacts with two moles of oxygen.
     c. one mole of nitrogen reacts with two moles of oxygen.
28. How many moles of Cl₂ are required to react with 5.00 moles of CH₄?
       CH₄ + 2 Cl₂ -----> CH₂Cl₂ + 2 HCl
     a. 2.50 moles         b. 5.00 moles         c. 10.0 moles
29. Magnesium metal reacts with nitrogen to produce magnesium nitride according
      to the following reaction:   3 Mg(s) +      N₂(g) ---> Mg₃N₂(s).
      What mass of nitrogen is required to react with 5.00 moles of magnesium?
     a. 420. g         b. 163. g         c. 24.3 g           d. 46.7 g
30. In the following reaction, if 23.0 g of NO₂ was produced from the decomposition of nitric acid.
       What amount of H₂O is also produced?         4 HNO₃(aq) ---> 4 NO₂(aq) + 2 H₂O(l) + O₂(g)
     a. 0.250 mol             b. 0.500 mol             c. 4.00 mol             d. 23.0 mol
31. What mass of iron can be extracted from 10.0 kg of iron(III) oxide, Fe₂O₃, according to
       the following reaction?    Fe₂O₃(s) + 3 CO(g) ---> 2 Fe(s) + 3 CO₂(g)
     a. 6.99 kg      b. 7.51 kg      c. 3.33 kg      d. 5.82 kg
32. What mass of oxygen is required to completely combust 1.00 g of CH₄?
     a. 3.99 g         b. 2.99 g         c. 1.99 g         d. 0.99 g
33. Consider the following equation: 3 X + 2 Y ---> Z. If 1 mole of X and 1 mole of Y are mixed
       and allowed to react, which will be completely consumed in the reaction?
     a. X         b. Y
34. In the reaction 2 Na(s) + H₂(g) ---> 2NaH(s), when 4.28 g of Na is reacted with 2.35 g of H₂,
       the total mass of the product and the leftover reactant is
     a. 2.35 g.         b. 4.47 g.         c. 6.63 g.         d. 8.10 g.
35. In the reaction Fe₂O₃(s) + 3 CO(g) ---> 2 Fe(s) + 3 CO₂(g), when 45.3 g of CO reacts
       with 79.8 g of Fe₂O₃, the limiting reagent is
     a. Fe₂O₃.         b. CO.         c. Fe.         d. CO₂.
36. What is the percent yield, if excess CaCO₃ is added to 4.78 g of HCl and produces 5.10 g
        of CaCl₂ according to the following reaction?    2 HCl(aq) + CaCO₃(s) ---> CaCl₂(aq) + H₂O(l) + CO₂(g)
     a. 96.2 %         b. 83.1 %         c. 70.2 %         d. 64.3 %
37. If 90 g of C₂H₆S are reacted with 200 g of O₂, how many grams of SO₂ could be produced?
        [MW C₂H₆S = 62.15 g/mol; O₂ = 32.00 g/mol; SO₂ = 64.07 g/mol]
                            2 C₂H₆S + 9 O₂ ----> 4 CO₂ + 6 H₂O + 2 SO₂
     a. 93 g SO₂         b. 85 g SO₂            c. 89 g SO₂         d. 97 g SO₂
38. Nitrogen reacts with chlorine to produce nitrogen trichloride according to the balanced equation
      shown below. When 0.100 mol of nitrogen reacted with an excess of chlorine gas, 8.425 g of
      nitrogen trichloride was isolated. Calculate the percent yield.         (MW NCl₃ = 120.36 g/mol)
                                N₂(g) + 3 Cl₂(g) ---> 2 NCl₃(l)
     a. 20%             b. 25%             c. 30%             d. 35%

1. d
2. b
3. b
4. d
5. c
6. a
7. d
8. b
9. a
10. d
11. b
12. a
13. d
14. a
15. a
16. d
17. b
18. a
19. d

20. c
21. c
22. b
23. c
24. b
25. d
26. a
27. c
28. c
29. d
30. a
31. a
32. a
33. a
34. c
35. a
36. c
37. c
38. d