Question 1

Which of the following best describes a gas evolution equation?

Accepted Answer

A molecular equation that involves the formation of CO$$_2$$ gas.

Question 2

In the reaction $$\mathrm{Na_2CO_3 (aq) + 2 HBr (aq) \rightarrow}$$, which of the following is the correct balanced molecular equation for the gas evolution process?

Accepted Answer

$$\mathrm{2 NaBr (aq) + CO_2$ (g) + H_2O (l)}$$

Question 3

What is the median product formed in the reaction between $$\mathrm{H^+}$$ and $$\mathrm{CO_3$^{2-}}$$?

Accepted Answer

$$\mathrm{H_2CO_3}$$

Question 4

In a gas evolution reaction, why is the median product often not shown in the final balanced equation?

Accepted Answer

Because it is unstable and decomposes into the final products.

Question 5

Given the reaction $$\mathrm{$$KHCO_3$$ (aq) + HCl (aq)}$$, what are the final products after the gas evolution process?

Accepted Answer

$$\mathrm{KCl (aq) + CO_2$ (g) + H_2O (l)}$$

Question 6

Which step in predicting the products of a gas evolution reaction involves swapping ionic partners?

Accepted Answer

Step 2

Question 7

If you mix $$\mathrm{$$CaCO_3$$ (aq)}$$ and $$\mathrm{2 HCl (aq)}$$, what gas is evolved?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 8

Which of the following is the correct ionic equation for the reaction between $$\mathrm{Na_2CO_3}$$ and $$\mathrm{HBr}$$?

Accepted Answer

$$\mathrm{2 Na^+ (aq) + CO_3$^{2-} (aq) + 2 H^+ (aq) + 2 Br^- (aq) \rightarrow 2 Na^+ (aq) + 2 Br^- (aq) + CO_2$ (g) + H_2O (l)}$$

Question 9

A student mixes $$\mathrm{K_2CO_3}$$ and $$\mathrm{2 $$HNO_3$$} in $$water. What is the balanced molecular equation for the gas evolution reaction?

Accepted Answer

$$\mathrm{K_2CO_3 (aq) + 2 $$HNO_3$$ (aq) \rightarrow 2 $$KNO_3$$ (aq) + CO_2$ (g) + H_2O (l)}$$

Question 10

Why is it necessary to break up hydrogen sulfide ($$\mathrm{H_2S}) $$into water and gas in some gas evolution reactions?

Accepted Answer

Because $$\mathrm{H_2S} is a $$gas and escapes from solution, leaving water behind.

Question 11

Which of the following is a correct step in predicting the products of a gas evolution reaction?

Accepted Answer

Balance the molecular equation after identifying the final products.

Question 12

A patient is given an antacid containing $$\mathrm{$$CaCO_3$$} to $$neutralize stomach acid ($$\mathrm{HCl}). $$What gas is produced in this reaction?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 13

Which of the following is the correct net ionic equation for the reaction between $$\mathrm{$$KHCO_3$$}$$ and $$\mathrm{HCl}$$?

Accepted Answer

$$\mathrm{$$HCO_3$$^- (aq) + H^+ (aq) \rightarrow CO_2$ (g) + H_2O (l)}$$

Question 14

When $$\mathrm{H_2CO_3} is $$formed as a median product in a reaction, what happens next?

Accepted Answer

It decomposes into $$\mathrm{CO_2$}$$ and $$\mathrm{H_2O}.$$

Question 15

Which of the following is a real-world application of gas evolution reactions?

Accepted Answer

Formation of $$\mathrm{CO_2$} in $$baking when baking soda reacts with acid.

Question 16

If $$\mathrm{Na_2CO_3} is $$mixed with $$\mathrm{2 $$HNO_3$$}$$, what is the final balanced equation?

Accepted Answer

$$\mathrm{Na_2CO_3 (aq) + 2 $$HNO_3$$ (aq) \rightarrow 2 $$NaNO_3$$ (aq) + CO_2$ (g) + H_2O (l)}$$

Question 17

Which of the following is NOT a step in predicting the products of a gas evolution reaction?

Accepted Answer

Ignore balancing the final molecular equation.

Gas Evolution Equations in GOB Chemistry

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