Carbon dioxide reacts with calcium hydroxide to form calcium carbonate and water.

Ca(OH)2 + CO2 → CaCO3 + H2O

From the above reaction, what can we conclude about CO2?

(A) Acidic

(B) Basic

(C) Amphoteric

(D) Neutral

To analyze the reaction between carbon dioxide (CO2) and calcium hydroxide (Ca(OH)2), we need to consider the nature of CO2 in this context. The reaction produces calcium carbonate (CaCO3) and water (H2O), which gives us clues about the properties of CO2. Let's break it down step by step.

Understanding the Reaction

The equation you provided is:

Ca(OH)2 + CO2 → CaCO3 + H2O

Here, calcium hydroxide, a strong base, reacts with carbon dioxide. When CO2 combines with Ca(OH)2, it forms calcium carbonate, which is a salt, and water. This indicates that CO2 is acting as an acid in this reaction.

Properties of CO2

• Acidic Nature: Carbon dioxide is known to form carbonic acid (H2CO3) when dissolved in water. This is a key characteristic of acids, which can donate protons (H+) in solution.
• Reaction with Bases: The fact that CO2 reacts with a strong base like calcium hydroxide to produce a salt and water further supports its acidic behavior. In acid-base reactions, acids react with bases to form salts and water.

Evaluating the Options

Now, let's look at the options provided:

• (A) Acidic: This is a strong contender, as CO2 exhibits acidic properties in this reaction.
• (B) Basic: This is incorrect because CO2 does not accept protons or produce hydroxide ions in this context.
• (C) Amphoteric: While some substances can act as both acids and bases, CO2 primarily behaves as an acid in this reaction.
• (D) Neutral: This option does not apply, as CO2 clearly participates in an acid-base reaction.

Conclusion

Based on the evidence from the reaction and the properties of CO2, we can confidently conclude that the correct answer is (A) Acidic. This highlights the role of carbon dioxide as an acid when it interacts with bases like calcium hydroxide.