Below are two reactions students wrote for the balanced equation of carbonate ion acting as a Bronsted-Lowry base in water: Choose the answer which correctly describes these equations (1) CO32- (aq) Hzo () HCO3 (aq) OH (aq) (2) CO3?- (aq) 2 HzO () == HCO3 (aq) H3O’ (aq) both (1) and are correct Only (2) is correct and (1) is incorrect: both (1) and [ (2) are incorrect Only (1) is correct and (2) is incorrect:
The Correct Answer and Explanation is:
The correct answer is: Only (1) is correct and (2) is incorrect.
Explanation:
Let’s break down both reactions:
Reaction (1):
CO32−(aq)+H2O(l)⇌HCO3−(aq)+OH−(aq)\text{CO}_3^{2-} (\text{aq}) + \text{H}_2\text{O} (\text{l}) \rightleftharpoons \text{HCO}_3^- (\text{aq}) + \text{OH}^- (\text{aq})CO32−(aq)+H2O(l)⇌HCO3−(aq)+OH−(aq)
- In this reaction, the carbonate ion (CO32−\text{CO}_3^{2-}CO32−) is acting as a Bronsted-Lowry base, which means it is accepting a proton (H+\text{H}^+H+) from water.
- When the carbonate ion (CO32−\text{CO}_3^{2-}CO32−) accepts a proton from water, it forms bicarbonate (HCO3−\text{HCO}_3^-HCO3−) and hydroxide ions (OH−\text{OH}^-OH−).
- This is a correct representation of a Bronsted-Lowry base behavior because carbonate ion is accepting a proton to produce the conjugate acid (bicarbonate) and hydroxide.
Reaction (2):
CO32−(aq)+2H2O(l)⇌HCO3−(aq)+H3O+(aq)\text{CO}_3^{2-} (\text{aq}) + 2 \text{H}_2\text{O} (\text{l}) \rightleftharpoons \text{HCO}_3^- (\text{aq}) + \text{H}_3\text{O}^+ (\text{aq})CO32−(aq)+2H2O(l)⇌HCO3−(aq)+H3O+(aq)
- In this reaction, the carbonate ion (CO32−\text{CO}_3^{2-}CO32−) is supposedly acting as a Bronsted-Lowry base, but the product here includes hydronium (H3O+\text{H}_3\text{O}^+H3O+) ions, which would imply that the carbonate ion is acting as an acid (not a base).
- In fact, the carbonate ion should not produce hydronium ions (H3O+\text{H}_3\text{O}^+H3O+) when it acts as a base. It should form hydroxide ions (OH−\text{OH}^-OH−) instead, which is seen in Reaction (1).
- Therefore, Reaction (2) is incorrect because it does not properly represent the behavior of carbonate ion as a Bronsted-Lowry base.
Conclusion:
- Reaction (1) correctly describes the behavior of the carbonate ion acting as a Bronsted-Lowry base by accepting a proton and forming hydroxide ions.
- Reaction (2) is incorrect because it implies the formation of hydronium ions, which would suggest an acidic behavior rather than a basic one.
Thus, the correct answer is: Only (1) is correct and (2) is incorrect.
