Question 1

Which of the following is NOT considered evidence of a chemical reaction?

Accepted Answer

Bubbles form when water is boiled.

Question 2

Which of the following best describes what happens at the molecular level during the combustion of octane ($$\mathrm{C_8H_{18}}) in an $$automobile engine?

Accepted Answer

Octane and oxygen molecules react to form new substances, carbon dioxide and water.

Question 3

Which of the following is the correct balanced equation for the combustion of methane ($$\mathrm{CH_4$}) in $$oxygen?

Accepted Answer

$$\mathrm{CH_4$(g) + 2O_2(g) \rightarrow CO_2$(g) + 2H_2O(g)}$$

Question 4

When sodium chloride ($$\mathrm{NaCl}) $$dissolves in water, what species are present in the solution?

Accepted Answer

Only $$\mathrm{Na^+}$$ and $$\mathrm{Cl^-}$$ ions

Question 5

Which of the following compounds is insoluble in water according to the solubility rules?

Accepted Answer

$$\mathrm{AgCl}$$

Question 6

What is the net ionic equation for the reaction between aqueous solutions of silver nitrate ($$\mathrm{$$AgNO_3$$}) $$and sodium chloride ($$\mathrm{NaCl}$$)?

Accepted Answer

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

Question 7

Which of the following statements about balancing chemical equations is correct?

Accepted Answer

You should only change the coefficients in front of chemical formulas to balance the equation.

Question 8

A student mixes solutions of potassium iodide ($$\mathrm{KI}) $$and lead(II) nitrate ($$\mathrm{Pb(NO_3$)_2}) $$and observes a yellow solid forming. What type of reaction has occurred?

Accepted Answer

Precipitation reaction

Question 9

Which of the following is the correct molecular equation for the reaction between sodium carbonate ($$\mathrm{Na_2CO_3}) $$and copper(II) chloride ($$\mathrm{$$CuCl_2$$}) in $$aqueous solution?

Accepted Answer

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

Question 10

Which of the following best describes a strong electrolyte?

Accepted Answer

A compound that completely dissociates into ions in solution

Question 11

Which of the following is the correct net ionic equation for the neutralization reaction between hydrochloric acid ($$\mathrm{HCl}) $$and sodium hydroxide ($$\mathrm{NaOH}$$)?

Accepted Answer

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

Question 12

Which of the following reactions is an example of an oxidation–reduction (redox) reaction?

Accepted Answer

Combustion of methane: $$\mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O}$$

Question 13

Which of the following best describes a spectator ion?

Accepted Answer

An ion that is present in solution but does not participate in the reaction

Question 14

A solution of $$\mathrm{Ba(OH)_2} is $$mixed with a solution of $$\mathrm{Na_2SO_4}. $$What is the precipitate, if any, that forms?

Accepted Answer

$$\mathrm{$$BaSO_4$$(s)}$$

Question 15

Which of the following is a correct classification for the reaction: $$\mathrm{2KI(aq) + Pb(NO_3$)_2(aq) \rightarrow $$PbI_2$$(s) + 2KNO_3(aq)}$$?

Accepted Answer

Precipitation reaction

Question 16

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

Accepted Answer

$$\mathrm{Ag^+(aq) + NO_3$^-(aq) + Na^+(aq) + Cl^-(aq) \rightarrow AgCl(s) + Na^+(aq) + NO_3$^-(aq)}$$

Question 17

Which of the following is a real-world example of a gas evolution reaction?

Accepted Answer

Mixing vinegar (acetic acid) and baking soda (sodium bicarbonate) to produce bubbles

Question 18

Which of the following best describes a combustion reaction?

Accepted Answer

A reaction in which a substance reacts with $$\mathrm{O_2$} to $$form one or more oxygen-containing compounds and releases heat

Chemical Reactions: Evidence, Types, and Equations

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