Question 1

Which of the following observations is the BEST evidence that a chemical reaction has occurred?

Accepted Answer

A colorless solution turns yellow and a solid forms when two solutions are mixed.

Question 2

Which of the following is the correctly balanced chemical equation for the combustion of pentane ($$\mathrm{C_5H_{12}}$$)?

Accepted Answer

$$\mathrm{C_5H_{12}(l) + 8O_2(g) \rightarrow 5CO_2(g) + 6H_2O(g)}$$

Question 3

Which compound is insoluble in water according to the solubility rules?

Accepted Answer

$$\mathrm{AgBr}$$

Question 4

What is the net ionic equation for the reaction between aqueous solutions of $$\mathrm{$$BaCl_2$$}$$ and $$\mathrm{K_2SO_4}$$?

Accepted Answer

$$\mathrm{Ba$$^{2+}$$(aq) + SO_4$^{2-}(aq) \rightarrow $$BaSO_4$$(s)}$$

Question 5

Which of the following reactions is both a gas-evolution and an acid–base reaction?

Accepted Answer

$$\mathrm{2HCl(aq) + Na_2CO_3(aq) \rightarrow 2NaCl(aq) + H_2O(l) + CO_2$(g)}$$

Question 6

A student mixes solutions of $$\mathrm{Na_2CO_3}$$ and $$\mathrm{$$CuCl_2$$}. $$What is the balanced molecular equation for the reaction, and what type of reaction is it?

Accepted Answer

$$\mathrm{Na_2CO_3(aq) + $$CuCl_2$$(aq) \rightarrow $$CuCO_3$$(s) + 2NaCl(aq)}$$; precipitation reaction

Question 7

Which of the following is a redox reaction?

Accepted Answer

$$\mathrm{2Na(s) + Cl_2$(g) \rightarrow 2NaCl(s)}$$

Question 8

Which of the following best describes the process that occurs when $$\mathrm{$$BaCl_2$$}$$ dissolves in water?

Accepted Answer

$$\mathrm{$$BaCl_2$$}$$ dissociates completely into $$\mathrm{Ba$$^{2+}$$}$$ and $$\mathrm{2Cl^-}$$ ions.

Question 9

Which of the following is the correct net ionic equation for the reaction between $$\mathrm{HCl(aq)}$$ and $$\mathrm{NaOH(aq)}$$?

Accepted Answer

$$\mathrm{H^+(aq) + OH^-(aq) \rightarrow H_2O(l)}$$

Question 10

A solution of $$\mathrm{Pb(NO_3$)_2} is $$mixed with a solution of $$\mathrm{Na_2SO_4}. $$What is the net ionic equation for the reaction?

Accepted Answer

$$\mathrm{Pb$$^{2+}$$(aq) + SO_4$^{2-}(aq) \rightarrow $$PbSO_4$$(s)}$$

Question 11

Which of the following is a double-displacement reaction?

Accepted Answer

$$\mathrm{Ba(NO_3$)_2(aq) + K_2SO_4(aq) \rightarrow $$BaSO_4$$(s) + 2KNO_3(aq)}$$

Question 12

Which of the following reactions is a decomposition reaction that requires energy input?

Accepted Answer

$$\mathrm{2HgO(s) \xrightarrow{	ext{heat}} 2Hg(l) + O_2$(g)}$$

Question 13

Which of the following best explains why laundry detergents are more effective than hand soap in hard water?

Accepted Answer

Detergents contain substances that remove $$\mathrm{Ca$$^{2+}$$}$$ and $$\mathrm{Mg$$^{2+}$$}$$ ions by forming insoluble compounds, preventing soap scum.

Question 14

Which of the following is the correct balanced equation for the reaction of solid aluminum with aqueous sulfuric acid to form aqueous aluminum sulfate and hydrogen gas?

Accepted Answer

$$\mathrm{2Al(s) + 3H_2SO_4(aq) \rightarrow Al_2$(SO_4$)_3(aq) + 3H_2(g)}$$

Question 15

Which of the following is the correct net ionic equation for the reaction between $$\mathrm{$$AgNO_3$$(aq)}$$ and $$\mathrm{NaCl(aq)}$$?

Accepted Answer

$$\mathrm{Ag^+(aq) + Cl^-(aq) \rightarrow AgCl(s)}$$

Question 16

Which of the following reactions is a synthesis (combination) reaction?

Accepted Answer

$$\mathrm{2Na(s) + Cl_2$(g) \rightarrow 2NaCl(s)}$$

Question 17

Which of the following is the correct balanced equation for the combustion of ethanol ($$\mathrm{C_2H_5OH}$$)?

Accepted Answer

$$\mathrm{C_2H_5OH(l) + 3O_2(g) \rightarrow 2CO_2(g) + 3H_2O(g)}$$

Question 18

Which of the following is a single-displacement reaction?

Accepted Answer

$$\mathrm{Zn(s) + $$CuCl_2$$(aq) \rightarrow $$ZnCl_2$$(aq) + Cu(s)}$$

Question 19

A student mixes $$\mathrm{NH_4Cl(aq)}$$ and $$\mathrm{NaOH(aq)}. $$Which gas is evolved, and what is the net ionic equation for the gas-evolution reaction?

Accepted Answer

Ammonia ($$\mathrm{NH_3$}) is $$evolved; $$\mathrm{NH_4$^+(aq) + OH^-(aq) \rightarrow NH_3$(g) + H_2O(l)}$$

Ch 7: Chemical Reactions: Types, Equations, and Aqueous Chemistry

Study Guide - Practice Questions

Study Guide - Flashcards