Carbon Dioxide (CO2) Dissolves in Water to Give Acidic Solution

Carbon dioxide (CO2) is the gas that dissolves in water to give an acidic solution. When CO2 gas dissolves in water, it reacts with the water molecules to form carbonic acid (H2CO3). This reaction can be represented as follows:

CO2 + H2O ⇌ H2CO3

Explanation:

1. Carbon Dioxide Dissolving in Water
- When carbon dioxide gas is passed through water, it dissolves and forms a solution.
- The solubility of carbon dioxide in water is relatively high, meaning that a significant amount of CO2 can dissolve in water.

2. Formation of Carbonic Acid
- Once CO2 dissolves in water, it reacts with the water molecules to form carbonic acid (H2CO3).
- This reaction is a reversible reaction, meaning that carbonic acid can also dissociate back into carbon dioxide and water.

3. Equilibrium Reaction
- The reaction between carbon dioxide and water is an equilibrium reaction, which means that it can occur in both forward and backward directions.
- The equilibrium lies more towards the product side, meaning that carbon dioxide readily reacts with water to form carbonic acid.

4. Acidic Solution Formation
- The formation of carbonic acid results in the release of hydrogen ions (H+) in the solution.
- These hydrogen ions make the solution acidic in nature.
- The presence of hydrogen ions is responsible for the acidic properties of the solution.

5. Acid-Base Balance
- The carbonic acid formed by the dissolution of carbon dioxide in water is a weak acid.
- It can donate protons (H+) to water, making the solution acidic.
- However, carbonic acid can also dissociate back into carbon dioxide and water, reducing the concentration of hydrogen ions and decreasing the acidity of the solution.

In conclusion, carbon dioxide dissolves in water to form carbonic acid, which releases hydrogen ions and makes the solution acidic. This is why carbon dioxide is responsible for giving an acidic solution when dissolved in water.