Question 1

Which of the following is the correct net ionic equation for the reaction between sodium carbonate and hydrochloric acid, including the gas formation step?

Accepted Answer

$$2 \mathrm{H}^+ (aq) + \mathrm{CO}_3$$^{2-}$$ (aq) \rightarrow \mathrm{CO}_2 (g) + \mathrm{H}_2\mathrm{O} (l)$$

Question 2

Which of the following best describes the role of oxygen in the reaction $$2 \mathrm{H}_2 (g) + \mathrm{O}_2 (g) \rightarrow 2 \mathrm{H}_2\mathrm{O} (g)$$?

Accepted Answer

Oxygen is the oxidizing agent because it gains electrons.

Question 3

In the reaction $$\mathrm{Li}_2\mathrm{SO}_3 (aq) + 2 \mathrm{HCl} (aq) \rightarrow 2 \mathrm{LiCl} (aq) + \mathrm{SO}_2 (g) + \mathrm{H}_2\mathrm{O} (l)$$, what gas is produced and what is the net ionic equation?

Accepted Answer

Sulfur dioxide; $$\mathrm{SO}_3$$^{2-}$$ (aq) + 2 \mathrm{H}^+ (aq) \rightarrow \mathrm{SO}_2 (g) + \mathrm{H}_2\mathrm{O} (l)$$

Question 4

Which of the following statements about oxidation numbers is CORRECT?

Accepted Answer

Oxygen usually has an oxidation number of $$-2$$, except in peroxides where it is $$-1.$$

Question 5

Consider the reaction: $$2 \mathrm{K} (s) + 2 \mathrm{H}_2\mathrm{O} (l) \rightarrow 2 \mathrm{KOH} (aq) + \mathrm{H}_2 (g). $$Which element is oxidized and which is reduced?

Accepted Answer

Potassium is oxidized; hydrogen is reduced.

Question 6

Which of the following metals will NOT react with hydrochloric acid to produce hydrogen gas, based on the activity series?

Accepted Answer

Copper

Question 7

In the reaction $$\mathrm{CuCl}_2 (aq) + \mathrm{Zn} (s) \rightarrow \mathrm{ZnCl}_2 (aq) + \mathrm{Cu} (s)$$, which species is the reducing agent?

Accepted Answer

Zinc

Question 8

Assign the oxidation number to chromium in $$\mathrm{Cr}_2\mathrm{O}_7$$^{2-}$$.

Accepted Answer

$$+6$$

Question 9

Which of the following is an example of a disproportionation reaction?

Accepted Answer

$$\mathrm{Br}_2 \rightarrow \mathrm{BrO}_3^- + \mathrm{Br}^-$$

Question 10

Which of the following reactions is a combination reaction?

Accepted Answer

$$2 \mathrm{S} (s) + 3 \mathrm{O}_2 (g) \rightarrow 2 \mathrm{SO}_3 (g)$$

Question 11

Which of the following statements about the activity series is TRUE?

Accepted Answer

A metal higher in the activity series will displace a metal lower in the series from a compound.

Question 12

What is the oxidation number of nitrogen in the ammonium ion, $$\mathrm{NH}_4^+$$?

Accepted Answer

$$-3$$

Question 13

Which of the following reactions is a halogen displacement reaction that will proceed spontaneously?

Accepted Answer

$$\mathrm{Cl}_2 (g) + 2 \mathrm{NaBr} (aq) \rightarrow 2 \mathrm{NaCl} (aq) + \mathrm{Br}_2 (l)$$

Question 14

Balance the following redox reaction and identify the oxidizing agent: $$\mathrm{Mg} (s) + \mathrm{N}_2 (g) \rightarrow \mathrm{Mg}_3\mathrm{N}_2 (s).$$

Accepted Answer

Balanced: $$3 \mathrm{Mg} (s) + \mathrm{N}_2 (g) \rightarrow \mathrm{Mg}_3\mathrm{N}_2 (s)$$; oxidizing agent: $$\mathrm{N}_2$$

Question 15

Which of the following best describes a reducing agent in a redox reaction?

Accepted Answer

It is the substance that is oxidized and donates electrons.

Question 16

In the reaction $$\mathrm{Br}_2 (l) + 2 \mathrm{NaI} (aq) \rightarrow 2 \mathrm{NaBr} (aq) + \mathrm{I}_2 (s)$$, which element is reduced?

Accepted Answer

Bromine

Question 17

Which of the following compounds contains an element with a fractional oxidation number?

Accepted Answer

$$\mathrm{NaO}_2$$

Question 18

Which of the following is the correct balanced net ionic equation for the reaction between zinc metal and copper(II) sulfate solution?

Accepted Answer

$$\mathrm{Zn} (s) + \mathrm{Cu}^{2+} (aq) \rightarrow \mathrm{Zn}^{2+} (aq) + \mathrm{Cu} (s)$$

Question 19

Which of the following statements about transition metals is correct?

Accepted Answer

Transition metals can have multiple possible oxidation numbers.

Stoichiometry of Chemical Reactions: Acid-Base Gas Formation and Redox Reactions

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