7.1 Practice Problems

Attempt these problems as if they were real exam questions in an exam environment.

Only look up information if you get severely stuck. Never look at the solution until you have exhausted all efforts to solve the problem. Having to look up information or the solution should be an indicator that the previous layers (1–5) in the Structured Learning Approach have not been mastered.

  1. Which of the following statements is incorrect?

    1. A spectator ion is one that is in its aqueous form on one side of the reaction arrow, but in a solid form on the other side in a complete ionic equation.
    2. If you mix two salt solutions and notice a solid starting to form from the solutions, gathering at the bottom of the mixture flask, you can call the solid the “precipitate”.
    3. A net ionic equation does not include spectator ions.
    4. (aq) denotes a species dissolved in aqueous solution.
    5. Hydroxide ions often form insoluble compounds, but some hydroxides (like sodium hydroxide) are soluble in water.

    Solution


  2. In which of the below species does nitrogen have the highest (most positive) oxidation number?

    1. NaNO3
    2. N2
    3. NH3
    4. HNO2
    5. NO2–

    Solution


  3. What is the coefficient found in front of the H2O in the balanced combustion reaction equation between C4H10 and molecular oxygen?

    1. 5
    2. 10
    3. 13
    4. 26
    5. none of these

    Solution


  4. Identify the reaction below that corresponds to a decomposition reaction.

    1. 2NaClO3 → 2NaCl + 3O2
    2. BaCl2 + Na2SO4 → BaSO4 + 2NaCl
    3. CH4 + 2O2 → CO2 + 2H2O
    4. Mg + CaCl2 → MgCl2 + Ca
    5. 2H2 + O2 → 2H2O

    Solution


  5. Identify the reaction below that corresponds to a decomposition reaction

    1. Zn(NO3)2 + Ba(CH3COO)2 →
    2. Al(s) + ZnCl2 →
    3. Zn(s) + AlCl3 →
    4. KNO3 + NaCH3COO →
    5. none of these will produce products

    Solution


  6. 17.84 mL of 0.323 M FeCl3 and 10.65 mL of 0.752 M NaOH are reacted. How many moles of NaCl(aq) are produced if the following reaction goes to completion?
    \[\mathrm{FeCl_3}(aq) + 3\mathrm{NaOH}(aq) \longrightarrow \mathrm{3NaCl}(aq) + \mathrm{Fe(OH)_3}(s)\]

    1. 0.2001
    2. 0.0173
    3. 0.0940
    4. 0.0080
    5. 0.3510

    Solution


  7. What are the spectator ions for the following reaction:
    \[\mathrm{HCl} + \mathrm{Ca(OH)_2} \longrightarrow \mathrm{CaCl_2} + \mathrm{H_2O}\]

    1. Proton
    2. H2O
    3. Hydroxide
    4. Calcium and chloride
    5. Proton and hydroxide

    Solution


  8. What volume (in mL) of 0.223 M Mg(OH)2 is required to neutralize 26.7 mL of 1.2 M HI?

    1. 88.93
    2. 0.223
    3. 71.84
    4. 0.072
    5. 52.36

    Solution


  9. How many grams of AgCl (143.35 g mol–1) are produced by the unbalanced reaction below if 0.483 moles of silver nitrate are reacted with 0.234 moles nickel(II) chloride?
    \[\mathrm{AgNO_3} + ~\mathrm{NiCl_2} ~\longrightarrow ~\mathrm{AgCl} + ~\mathrm{Ni(NO_3)_2}\]

    1. 69.2
    2. 118.96
    3. 33.53
    4. 67.1
    5. 59.48

    Solution


  10. Which of the following is false for the equation:
    \[\mathrm{CH_3OH} + \mathrm{O_2} \longrightarrow \mathrm{CO_2} + \mathrm{H_2O}\]

    1. The reaction is a combustion reaction
    2. O2 is the oxidizing agent
    3. The reaction is not balanced
    4. Oxygen is reduced
    5. The oxidation state of carbon in CO2 is –4

    Solution


  11. If 4.4 mol of A reacts with 5.5 mol of B, which reactant will be the limiting reagent according to the following reaction?
    \[\mathrm{2A} + \mathrm{3B} \longrightarrow \mathrm{A_2B_3}\]

    1. A
    2. B
    3. Both A and B will completely react
    4. Not enough information
    5. A2B3

    Solution


  12. Identify the appropriately labeled atoms/molecules (below) for the following reaction:
    \[\mathrm{CH_4}(g) + \mathrm{2O_2}(g) \longrightarrow \mathrm{CO_2}(g) + \mathrm{2H_2O}(l)\]

    Answer Reduced Species Oxidized Species Reducing Agent Oxidizing Agent

    A

    O

    C

    CH4

    O2

    B

    C

    O

    O2

    CH4

    C

    O

    C

    O

    C

    D

    C

    O

    C

    O

    E

    CH4

    O2

    O

    C

    Solution


  13. Considering the balanced reaction below, select the oxidation half–reaction for this process:
    \[\mathrm{7Ca + 2KMnO_4} \longrightarrow \mathrm{7CaO} + \mathrm{2Mn} + \mathrm{K_2O}\]

    1. K+ → K2+ + e–
    2. O4– + 2e– → O2–
    3. Ca → Ca2+ + 2e–
    4. MnO4– + 7e– → Mn + 4O2–
    5. Mn2+ → Mn + 2e–

    Solution


  14. Identify the true statement below.

    1. Reduction describes the gain of an electron.
    2. Oxidation describes the gain of an electron.
    3. Mn(s) → Mn2+ is an example of reduction.
    4. Mn2+ → Mn(s) is an example of oxidation.
    5. None of these statements are true.

    Solution


  15. Using the bond order to rank the strength of the chemical bond between carbon and oxygen in the following compounds with decreasing bond dissociation energy. The Lewis structures of these compounds are shown below.

    1. A > D > C > B
    2. D > B > C > A
    3. A > C > D > B
    4. B > D > C > A
    5. D > C > B > A

    Solution




"Chemistry I: Online Resource" was prepared by Eric Van Dornshuld.    |    Release: Alpha 1.0
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