Question 1

Which of the following best describes a gas-evolution reaction in aqueous solution?

Accepted Answer

A reaction in which two aqueous solutions mix to form a gaseous product that bubbles out of solution.

Question 2

What is the balanced molecular equation for the gas-evolution reaction that occurs when aqueous hydrochloric acid is mixed with aqueous sodium bicarbonate?

Accepted Answer

$$HCl(aq) + $$NaHCO_3$$(aq) \rightarrow H_2O(l) + CO_2$(g) + NaCl(aq)$$

Question 3

In the reaction $$2HCl(aq) + Na_2CO_3(aq) \rightarrow 2NaCl(aq) + H_2O(l) + CO_2$(g)$$, which compound is responsible for the gas evolution?

Accepted Answer

$$CO_2$$

Question 4

Which of the following reactions is an example of a gas-evolution reaction where the gaseous product forms directly?

Accepted Answer

$$2HCl(aq) + K_2S(aq) \rightarrow H_2S(g) + 2KCl(aq)$$

Question 5

Which statement about oxidation and reduction is correct?

Accepted Answer

Oxidation is the loss of electrons; reduction is the gain of electrons.

Question 6

Assign the oxidation state to sulfur in $$SO_2.$$

Accepted Answer

+4

Question 7

Which of the following is NOT a redox reaction?

Accepted Answer

$$2HBr(aq) + Ca(OH)_2(aq) \rightarrow 2H_2O(l) + $$CaBr_2$$(aq)$$

Question 8

In the reaction $$Mg(s) + 2H_2O(l) \rightarrow Mg(OH)_2(aq) + H_2$(g)$$, which element is oxidized?

Accepted Answer

Magnesium

Question 9

What is the oxidation state of nitrogen in $$NO_3$$^-$$?

Accepted Answer

+5

Question 10

Which of the following is the correct definition of an oxidizing agent?

Accepted Answer

A substance that causes the oxidation of another substance and is itself reduced.

Question 11

In the reaction $$Zn(s) + Fe$$^{2+}$$(aq) \rightarrow Zn$$^{2+}$$(aq) + Fe(s)$$, which species is the reducing agent?

Accepted Answer

Zn(s)

Question 12

Which rule has the highest priority when assigning oxidation states in compounds?

Accepted Answer

The oxidation state of group 1A metals is always +1.

Question 13

A student mixes aqueous hydrobromic acid with aqueous potassium sulfite. What is the expected gaseous product?

Accepted Answer

$$SO_2$$

Question 14

Which of the following best explains why $$H_2CO_3(aq) is $$considered an intermediate in gas-evolution reactions?

Accepted Answer

It decomposes rapidly to form $$CO_2(g$$)$$ and H_2O(l$$)$$.

Question 15

In the reaction $$2Na(s) + Cl_2$(g) \rightarrow 2NaCl(s)$$, what is the oxidation state of sodium in the product?

Accepted Answer

+1

Question 16

Which of the following is a correct statement about the sum of oxidation states in a neutral molecule?

Accepted Answer

The sum equals zero.

Question 17

In the reaction $$2Mg(s) + O_2$(g) \rightarrow 2MgO(s)$$, which element is reduced?

Accepted Answer

Oxygen

Question 18

Which of the following is a common misconception about redox reactions?

Accepted Answer

Redox reactions always involve oxygen.

Question 19

A patient is given a solution containing $$NaHCO_3$$ and $$HCl. $$What gas will be produced in the patient's stomach?

Accepted Answer

$$CO_2$$

Gas-Evolution and Redox Reactions

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