In the reaction between sodium carbonate and acetic acid, what does the evolution of gas imply about the involved species? a. Carbonate is a stronger base than acetate. b. Carbonic acid is a stronger acid than acetic acid. c. The proton is transferred from carbonic acid to acetate. d. The proton is transferred from carbonate to acetic acid.
The Correct Answer and Explanation is:
The correct answer is a. Carbonate is a stronger base than acetate.
Explanation:
When sodium carbonate (Na2CO3) reacts with acetic acid (CH3COOH), a gas (carbon dioxide, CO2) is evolved. This is because acetic acid, which is a weak acid, reacts with the carbonate ion (CO3^2-) to form carbonic acid (H2CO3). However, carbonic acid is unstable and decomposes rapidly into carbon dioxide and water:Na2CO3(aq)+2CH3COOH(aq)→2CH3COONa(aq)+H2O(l)+CO2(g)\text{Na}_2\text{CO}_3 (aq) + 2\text{CH}_3\text{COOH} (aq) \rightarrow 2\text{CH}_3\text{COONa} (aq) + H_2O (l) + CO_2 (g)Na2CO3(aq)+2CH3COOH(aq)→2CH3COONa(aq)+H2O(l)+CO2(g)
The evolution of carbon dioxide gas is a key feature of this reaction. The underlying chemical process shows that carbonate (CO3^2-) acts as a base by accepting a proton (H+) from acetic acid. This implies that carbonate is a stronger base than acetate (CH3COO^-) because it is able to more readily accept a proton and facilitate the formation of carbonic acid.
- Carbonate vs. Acetate: Carbonate is a stronger base than acetate. This is because the carbonate ion (CO3^2-) has a high tendency to accept a proton, and its conjugate acid (carbonic acid, H2CO3) is unstable, leading to the evolution of CO2 gas. In contrast, acetate (CH3COO^-) is a weaker base because it has a lesser affinity for protons.
- Carbonic acid: While carbonic acid is a weak acid, its decomposition into CO2 gas indicates that the proton transfer is happening from carbonic acid to carbonate. The evolution of gas suggests that the proton transfer from acetic acid to carbonate is a significant driving force.
Thus, the reaction demonstrates that carbonate is a stronger base than acetate because it leads to the formation and decomposition of carbonic acid, resulting in the release of CO2 gas.
