Question 1

Which statement best describes the Law of Conservation of Mass as it applies to chemical reactions?

Accepted Answer

The total mass of reactants equals the total mass of products because atoms are rearranged, not created or destroyed.

Question 2

Given the unbalanced equation for the combustion of methane: $$\mathrm{CH_4$ + O_2$ \rightarrow CO_2$ + H_2O}$$, what are the correct coefficients to balance the equation?

Accepted Answer

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

Question 3

Which of the following reactions is a precipitation reaction?

Accepted Answer

$$\mathrm{Ba(NO_3$)_2 (aq) + K_2CrO_4 (aq) \rightarrow $$BaCrO_4$$ (s) + 2KNO_3 (aq)}$$

Question 4

A student mixes aqueous solutions of sodium chloride and silver nitrate. What is the net ionic equation for the reaction?

Accepted Answer

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

Question 5

Which of the following is the correct balanced equation for the decomposition of sodium chlorate, used in emergency breathing masks?

Accepted Answer

$$\mathrm{2NaClO_3 (s) \rightarrow 2NaCl (s) + 3O_2 (g)}$$

Question 6

Which of the following best describes a neutralization reaction?

Accepted Answer

A reaction in which an acid reacts with a base to produce water and a salt.

Question 7

What is the net ionic equation for the neutralization reaction between potassium hydroxide and nitric acid?

Accepted Answer

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

Question 8

Which of the following statements about oxidation and reduction is correct?

Accepted Answer

Oxidation is the loss of electrons or an increase in oxygen, and reduction is the gain of electrons or a decrease in oxygen.

Question 9

In the reaction $$\mathrm{Cu (s) + 2AgNO_3 (aq) \rightarrow 2Ag (s) + Cu(NO_3$)_2 (aq)}$$, which species is oxidized and which is reduced?

Accepted Answer

Cu is oxidized, Ag is reduced.

Question 10

Which of the following is the correct balanced equation for the neutralization reaction between aqueous HBr and Ba(OH)$$_2$$?

Accepted Answer

$$\mathrm{2HBr (aq) + Ba(OH)_2 (aq) \rightarrow 2H_2O (l) + $$BaBr_2$$ (aq)}$$

Question 11

Which of the following reactions is a redox reaction?

Accepted Answer

$$\mathrm{2AgNO_3 (aq) + Cu (s) \rightarrow 2Ag (s) + Cu(NO_3$)_2 (aq)}$$

Question 12

What is the oxidation number of sulfur in $$\mathrm{H_2SO_4}$$?

Accepted Answer

+6

Question 13

Which of the following best describes a reducing agent?

Accepted Answer

A substance that loses electrons and causes reduction.

Question 14

A patient’s pacemaker battery relies on redox reactions. Which real-world process is most similar to the chemistry in the battery?

Accepted Answer

Combustion of gasoline in a car engine.

Question 15

Which of the following is the correct net ionic equation for the precipitation reaction between AgNO$$_3 (aq) $$and ZnCl$$_2 (aq$$)?

Accepted Answer

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

Question 16

Which of the following is a correct rule for assigning oxidation numbers?

Accepted Answer

Oxygen is usually assigned an oxidation number of -2.

Question 17

In the reaction $$\mathrm{2Al (s) + 3Cl_2 (g) \rightarrow 2AlCl_3 (s)}$$, which element is oxidized and which is reduced?

Accepted Answer

Al is oxidized, Cl is reduced.

Question 18

Which of the following reactions would you classify as a neutralization reaction?

Accepted Answer

$$\mathrm{HCl (aq) + Ca(OH)_2 (aq) \rightarrow H_2O (l) + $$CaCl_2$$ (aq)}$$

Classification and Balancing of Chemical Reactions: Study Notes for General, Organic, and Biological Chemistry

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