Reaction of Carbon Dioxide with Calcium Hydroxide

This question asks about the product formed when carbon dioxide gas (\(CO_2\)) is passed through or reacts with calcium hydroxide solution (\((Ca(OH)_2)\)). This is a common chemical reaction often demonstrated in labs.

Understanding the Reactants

• Carbon Dioxide (\(CO_2\)): A colorless gas, slightly acidic in nature, commonly found in the atmosphere and produced during respiration and combustion.
• Calcium Hydroxide (\((Ca(OH)_2)\)): Also known as slaked lime or lime water when dissolved in water. It is a base.

The Chemical Reaction

When carbon dioxide gas is bubbled through calcium hydroxide solution (lime water), a chemical reaction occurs. This reaction is essentially an acid-base reaction where the acidic carbon dioxide reacts with the basic calcium hydroxide.

The balanced chemical equation for this reaction is:

\( CO_2 + Ca(OH)_2 \rightarrow CaCO_3 + H_2O \)

In this reaction:

• Carbon Dioxide (\(CO_2\)) reacts with Calcium Hydroxide (\((Ca(OH)_2)\)).
• The products formed are Calcium Carbonate (\(CaCO_3\)) and Water (\(H_2O\)).

Calcium carbonate (\(CaCO_3\)) is an insoluble salt and appears as a white precipitate, causing the lime water to turn milky or cloudy. This is a classic test for the presence of carbon dioxide.

Analysis of Options

Let's look at the options provided:

• 1. Calcium carbonate (\(CaCO_3\)): This is formed as a product in the reaction between \(CO_2\) and \(Ca(OH)_2\).
• 2. Calcium oxide (\(CaO\)): This is also known as quicklime. It is not directly formed in this reaction. It is formed when calcium carbonate is heated strongly.
• 3. Carbon monoxide (\(CO\)): This is a toxic gas and is not a product of this specific reaction.
• 4. Methane (\(CH_4\)): This is a hydrocarbon gas and is unrelated to the reaction between carbon dioxide and calcium hydroxide.

Conclusion

Based on the chemical reaction and analysis, the substance formed when carbon dioxide reacts with calcium hydroxide is Calcium carbonate.