General chemistry
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1. How many formula units are there in 2.5 moles of MgCl2?
A) 2.5 B) 7.5 C) 1.5 1024 D) 4.5 1024 E) 4.2 10–24
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2. How many chloride ions are present in 0.100 mol of MgCl2?
A) 0.200 Cl– ions D) 3.32 10–25 Cl– ions
B) 6.02 1022 Cl– ions E) 3.01 1024 Cl– ions
C) 1.20 1023 Cl– ions
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3. How many nitrate ions are present in 0.200 mol of Zn(NO3)2?
A) 1.20 1023 NO3– ions D) 6.64 10–25 NO3– ions
B) 2.41 1023 NO3– ions E) 0.400 NO3– ions
C) 3.01 1024 NO3– ions
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4. Consider the following chemical equations. Select the equations that represent chemical reactions, rather than physical changes.
I. CH4(g) + O2(g) CO2(g) + H2O(g)
II. C2H5OH(l) C2H5OH(g)
III. NaOH(s) Na+(aq) + OHˉ(aq)
A) I, II, and III D) II and III only
B) I and II only E) I only
C) I and III only
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5. Calculate the molar mass of CuSO4·5H2O.
A) 159.62 g/mol D) 185.72 g/mol
B) 249.70 g/mol E) 446.48 g/mol
C) 177.64 g/mol
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6. If 4.05 1023 molecules of a substance have a mass of 86.2 g, what is the molar mass of the substance?
A) 128 g/mol D) 4.70 1021 g/mol
B) 3.49 1025 g/mol E) 58.0 g/mol
C) 2.13 1022 g/mol
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7. Consider the following chemical equations. Select the equations that represent chemical reactions, rather than physical changes.
I. 2NO(g) + O2(g) 2NO2(g)
II. CO2(s) CO2(g)
III. Pb(NO3)2(aq) + 2AgCl(aq) PbCl2(s) + 2AgNO3(aq)
A) I, II, and III D) II and III only
B) I and II only E) I only
C) I and III only
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8. Write a complete, balanced equation for the reaction that occurs when sodium metal reacts with water to form hydrogen gas and aqueous sodium hydroxide.
A) Na(s) + H2O(l) NaOH(aq) + H(g)
B) Na(s) + H2O(l) NaOH(aq) + H2(g)
C) Na(s) + 2H2O(l) NaOH(aq) + 2H2(g)
D) Na(s) + 2H2O(l) 2NaOH(aq) + 2H2(g)
E) 2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g)
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9. Zinc metal will react with aqueous hydrochloric acid to produce aqueous zinc chloride and hydrogen gas. Write a complete, balanced equation for this reaction.
A) Zn(s) + HCl(aq) ZnCl(aq) + H(g)
B) Zn(s) + HCl(aq) ZnCl(aq) + H2(g)
C) Zn(s) + 2HCl(aq) ZnCl(aq) + H2(g)
D) Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)
E) 2Zn(s) + 2HCl(aq) 2ZnCl(aq) + H2(g)
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10. Calculate the number of moles of NaHCO3 (sodium bicarbonate, or baking soda) in a 5.0 g sample of this substance.
A) 0.096 mole D) 3.6 1022 moles
B) 0.060 mole E) 2.8 1023 mole
C) 420 moles
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11. Calculate the number of moles of NaOH (sodium hydroxide, an ingredient in drain cleaners and oven cleaners) in a 10.0 g sample of this substance.
A) 1.51 1023 moles D) 4.00 102 moles
B) 1.66 1023 mole E) 0.250 mole
C) 0.208 mole
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12. Calculate the number of moles of CaCO3 (calcium carbonate, or limestone) in a 20.0 g sample of this substance.
A) 2.00 103 moles D) 1.36 103 moles
B) 0.200 mole E) 1.20 103 moles
C) 0.294 mole
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13. When solid ammonium carbonate is heated, it decomposes to form ammonia gas, carbon dioxide gas, and water vapor, so that the solid completely disappears. Write a complete, balanced equation for this reaction.
A) NH4CO3(s) NH3(g) + CO2(g) + H2O(g)
B) NH4CO3(s) NH2(g) + CO2(g) + H2O(g)
C) (NH4)2CO3(s) NH3(g) + CO2(g) + H2O(g)
D) (NH4)2CO3(s) NH3(g) + CO2(g) + 3H2O(g)
E) (NH4)2CO3(s) 2NH3(g) + CO2(g) + H2O(g)
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14. Balance the following skeletal equation: C2H5OH(l) + O2(g) CO2(g) + H2O(g).
A) C2H5OH(l) + O2(g) CO2(g) + 3H2O(g)
B) C2H5OH(l) + O2(g) 2CO2(g) + 3H2O(g)
C) C2H5OH(l) + 2O2(g) 2CO2(g) + 3H2O(g)
D) C2H5OH(l) + 3O2(g) 2CO2(g) + 3H2O(g)
E) 2C2H5OH(l) + 3O2(g) 4CO2(g) + 3H2O(g)
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15. Balance the following skeletal equation: NH3(g) + O2(g) NO2(g) + H2O(g).
A) 4NH3(g) + 7O2(g) 4NO2(g) + 6H2O(g)
B) 2NH3(g) + 2O2(g) 2NO2(g) + 3H2O(g)
C) 2NH3(g) + O2(g) NO2(g) + 2H2O(g)
D) NH3(g) + O2(g) NO2(g) + 2H2O(g)
E) NH3(g) + O2(g) NO2(g) + H2O(g)
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16. Balance the following skeletal equation:
Ba(NO3)2(aq) + K2SO4(aq) BaSO4(s) + KNO3(aq)
A) Ba(NO3)2(aq) + K2SO4(aq) BaSO4(s) + KNO3(aq)
B) 2Ba(NO3)2(aq) + K2SO4(aq) 2BaSO4(s) + KNO3(aq)
C) 2Ba(NO3)2(aq) + 2K2SO4(aq) 2BaSO4(s) + 2KNO3(aq)
D) 2Ba(NO3)2(aq) + 2K2SO4(aq) 2BaSO4(s) + 3KNO3(aq)
E) Ba(NO3)2(aq) + K2SO4(aq) BaSO4(s) + 2KNO3(aq)
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17. After the following equation is properly balanced, what is the coefficient in front of O2?
S8(s) + O2(g) SO3(g)
A) 2 B) 3 C) 8 D) 12 E) 16
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18. A reaction which has two elements as reactants and one compound as a product is:
A) a decomposition reaction. D) a double-displacement reaction.
B) a combination reaction. E) a combustion reaction.
C) a single-displacement reaction.
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19. A solution of silver nitrate is mixed with a solution of sodium chloride, resulting in a precipitate of silver chloride and a solution of sodium nitrate. The class of this reaction is:
A) decomposition reaction. D) double-displacement reaction.
B) combination reaction. E) combustion reaction.
C) single-displacement reaction.
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20. A piece of magnesium metal is placed in a solution of hydrochloric acid, resulting in the formation of hydrogen gas and a solution of magnesium chloride. The class of this reaction is:
A) decomposition reaction. D) double-displacement reaction.
B) combination reaction. E) combustion reaction.
C) single-displacement reaction.
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21. The class of the reaction shown in the figure is:
A) decomposition reaction. D) double-displacement reaction.
B) combination reaction. E) combustion reaction.
C) single-displacement reaction.
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22. Write and balance the equation for the decomposition reaction that occurs when Mercury(II) oxide decomposes to its elements.
A) 2HgO(s) 2Hg(l) + O2(g) D) HgO2(s) Hg(l) + 2O(g)
B) Hg2O(s) 2Hg(l) + O2(g) E) 2Hg(l) +O2(g) HgO2(s)
C) HgO(s) Hg(l) + O2(g)
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23. When writing a net ionic equation, how would Mg(NO3)2(aq) be represented?
A) Mg2+(aq) + 2NO3–(aq) D) Mg(aq) + N2(aq) + 3O2(aq)
B) Mg2+(aq) + NO3–(aq) E) Mg2+(aq) + 2N3–(aq) + 6O2–(aq)
C) Mg2+(aq) + (NO3)2–(aq)
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24. Write and balance a net ionic equation for the reaction between hydrochloric acid and potassium hydroxide.
A) HCl(aq) + KOH(aq) KCl(aq) + H2O(l)
B) H+(aq) + O2ˉ(aq) OHˉ(aq)
C) H+(aq) + OHˉ(aq) H2O(l)
D) Clˉ(aq) + OH+(aq) OHCl(aq)
E) K+(aq) + Clˉ(aq) KCl(aq)
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25. Write and balance a net ionic equation for the reaction between iron(II) chloride and potassium hydroxide to form iron(II) hydroxide and potassium chloride.
A) Fe2Cl(aq) + OHˉ(aq) FeOH(s) + Clˉ(aq)
B) Fe2+(aq) + OHˉ(aq) FeOH(s)
C) Fe2+(aq) + 2OHˉ(aq) Fe(OH)2(s)
D) 2Clˉ(aq) + 2K+(aq) 2KCl(s)
E) 2Clˉ(aq) + 2K+(aq) 2K(s) + Cl2(g)
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26. When potassium metal is placed in water, will a reaction occur? If so, what is the balanced equation for the reaction?
A) No reaction will occur.
B) Yes. 2K(s) + 2H2O(l) 2K(OH)2(aq) + H2(g)
C) Yes. 2K(s) + 2H2O(l) 2KOH(aq) + H2(g)
D) Yes. 2K(s) + 2H2O(l) 2KH2O(aq)
E) Yes. 2K(s) + 2H2O(l) 2KOH(aq) + 2H2(g)
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27. When iron metal is placed into a solution of hydrochloric acid, will a reaction occur? If so, what is the balanced equation for the reaction?
A) No reaction will occur.
B) Yes. 2Fe(s) + 2HCl(aq) 2FeCl(aq) + H2(g)
C) Yes. Fe(s) + 2HCl(aq) FeCl2(aq) + H2(g)
D) Yes. Fe(s) + 3HCl(aq) FeCl3(aq) + H2(g)
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28. When copper metal is placed in a solution of zinc nitrate, will a reaction occur? If so, what is the balanced equation for the reaction?
A) Yes. Cu(s) + Zn(NO3)2(aq) CuNO3(aq) + ZnNO3(aq)
B) Yes. Cu(s) + Zn2NO3(aq) CuNO3(aq) + Zn(aq)
C) Yes. Cu(s) + Zn(NO3)2(aq) Cu(NO3)2(aq) + Zn(s)
D) No reaction will occur.
E) Yes. Cu(s) + Zn2NO3(aq) CuNO3(aq) + 2Zn(aq)
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29. When heated, calcium carbonate (limestone) undergoes a decomposition reaction. Write a balanced equation for this reaction.
A) CaCO3(s) Ca(s) + CO3(g) D) 2CaCO3(s) 2CaO(s) + CO2(g)
B) CaCO3(s) Ca(s) + CO2(g) E) 2CaCO3(s) 2CaO(s) + 3CO2(g)
C) CaCO3(s) CaO(s) + CO2(g)
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30. Which of the following ionic compounds would be expected to be insoluble in water?
A) KCl B) PbI2 C) NH4NO3 D) CuSO4 E) NaCH3CO2
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31. Which of the following ionic compounds would be expected to be insoluble in water?
A) CaS B) Ca(NO3)2 C) Na2SO4 D) KI E) NaOH
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32. A 5.05 g sample of quartz (SiO2) contains 2.36 g of silicon. What are the percents of silicon and oxygen in quartz?
A) 53.3% Si and 46.7% O
B) 46.7% Si and 53.3% O
C) 29.9% Si and 70.1% O
D) 70.1% Si and 29.9% O
E) 46.7% Si, and insufficient information to calculate % O
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33. A 6.25 g sample of magnetite (Fe3O4) contains 4.52 g of Fe. What are the percents of iron and oxygen in magnetite?
A) 28.6% Fe and 71.4% O D) 27.7% Fe and 72.3% O
B) 42.8% Fe and 57.2% O E) 57.2% Fe and 42.8% O
C) 72.3% Fe and 27.7% O
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34. A 7.50 g sample of pyrite (FeS2) contains 3.49 g of iron. What are the percents of iron and sulfur in pyrite (also known as “Fool’s Gold” because of its golden color)?
A) 57.4% Fe and 42.6% S D) 46.5% Fe and 53.5% S
B) 66.7% Fe and 33.3% S E) 53.5% Fe and 46.5% S
C) 33.3% Fe and 66.7% S
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35. Malachite is a green colored mineral that is 57.5% copper. What mass of copper is present in a 250.0 g sample of malachite?
A) 63.6 g B) 127 g C) 435 g D) 36.5 g E) 144 g
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36. Barium sulfate is a compound used to assist in diagnosing medical problems through x-ray analysis and is 58.8% barium. What mass of barium is present in a 620 mg tablet of barium sulfate?
A) 81 mg B) 230 mg C) 360 mg D) 1100 mg E) 11 mg
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37. Which of the following statements is incorrect?
A) PH3 has 3 times as many hydrogen atoms as phosphorus atoms.
B) MgO has an equal number of magnesium ions and oxygen ions.
C) BaBr2 has half as many barium ions as bromide ions.
D) N2O5 has 2.5 times as many nitrogen atoms as oxygen atoms.
E) SF4 has 4 times as many fluorine atoms as sulfur atoms.
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38. Which of the following statements is incorrect?
A) CH4 has ¼ as many carbon atoms as hydrogen atoms.
B) H2O has twice as many oxygen atoms as hydrogen atoms.
C) SO3 has three times as many oxygen atoms as sulfur atoms.
D) P4O10 has 2.5 times as many oxygen atoms as phosphorus atoms.
E) SrF2 has twice as many fluoride ions as strontium ions.
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39. Which of the following statements is incorrect?
A) N2H4 has four times as many hydrogen atoms as nitrogen atoms.
B) SF4 has ¼ as many sulfur atoms as fluorine atoms.
C) SO2 has twice as many oxygen atoms as sulfur atoms.
D) Ca(NO3)2 has six times as many oxygen atoms as calcium ions.
E) H2SO4 has twice as many oxygen atoms as hydrogen atoms.
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40. How many moles are in a sample of ethylene glycol (commonly found in antifreeze), HOCH2CH2OH, that has a volume of 250.0 mL? The molar mass and density of ethylene glycol are 62.07 g/mol and 1.11 g/mL, respectively.
A) 4.47 mol D) 1.40 104 mol
B) 0.276 mol E) 1.72 104 mol
C) 3.63 mol
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41. How many oxygen atoms are in 75.0 g of SO3?
A) 225 atoms D) 1.69 1024 atoms
B) 0.937 atoms E) 4.52 1025 atoms
C) 5.64 1023 atoms
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42. What is the mass of 4.5 1023 molecules of SO2?
A) 2.9 1025 g B) 64 g C) 86 g D) 36 g E) 48 g
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43. What is the mass of 2.4 1023 molecules of NO2?
A) 75 g B) 18 g C) 1.2 102 g D) 1.1 1023 g E) 12 g
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44. Which of the following statements regarding empirical formulas, molecular formulas, and percent composition is correct?
A) The compounds NO2 and N2O4 have the same empirical formula.
B) The compounds NO2 and N2O4 have the same molecular formula.
C) The empirical formula of H2O2 is H2O.
D) The empirical formula of N2O5 is NO2.5.
E) The compounds PCl3 and PCl5 would have the same percent composition.
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45. Methyl butyrate is a compound that is partially responsible for the flavor of apples. It consists of 58.80% C, 9.87% H, and 31.33% O. What is the empirical formula of methyl butyrate?
A) C6H10O3 B) C5H10O2 C) CH2O D) C4.9H9.8O1.9 E) C4H9O2
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46. Acetaminophen is the active ingredient in Tylenol. It consists of 63.56% C, 6.00% H, 9.27% N, and 21.17% O. What is the empirical formula of acetaminophen?
A) C8H8NO2 B) C8H9NO2 C) C6HNO2 D) C5.3H5.9N0.7O1.3 E) C4H4NO
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47. Acetic acid has a molar mass of 60.05 g/mol and consists of 40.00% C, 6.714% H, and 53.29% O. What is the molecular formula of acetic acid?
A) C3.33H6.66O3.33 B) C3H6O3 C) CH2O D) C2H4O2 E) CH3O
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48. Butyric acid has a very unpleasant odor. It is present in some rotting foods, body odor and vomit. Butyric acid has a molar mass of 88.10 g/mol and consists of 54.53% C, 9.153% H, and 36.32% O. What is the molecular formula of butyric acid?
A) CH2O0.5 B) CH2O C) CH4O D) C2H4O E) C4H8O2
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49. Acetaminophen is the active ingredient in Tylenol. It consists of 63.56% C, 6.00% H, 9.27% N, and 21.17% O. What is the empirical formula of acetaminophen?
A) C8H8NO2 B) C8H9NO2 C) C6HNO2 D) C5.3H5.9N0.7O1.3 E) C4H4NO
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50. Which of the following statements regarding empirical and molecular formulas is correct?
A) Information on percent composition is all that is necessary to determine both an empirical and a molecular formula.
B) A compound with an empirical formula of CH2O and a molar mass of 90 g/mol would have a molecular formula of C3H6O3.
C) The compounds C2H4 and C3H6 have different empirical formulas.
D) The formula Ca2Cl4 is the correct empirical formula for calcium chloride.
E) The compound benzene has a molecular formula of C6H6, so its empirical formula would be C3H3.