Add Hcl and Caco3 and then result to this will form cacl2, h20 and c02, I so to test for presence of co2 pass the gas through lime water that is calcium hydroxide then if it turn milky then co2 is present.

Activity to Detect the Presence of CO2 in Chemical Reaction

One common method to detect the presence of carbon dioxide (CO2) in a chemical reaction is through the use of limewater. Limewater is a clear, colorless solution of calcium hydroxide (Ca(OH)2) in water and can be used as an indicator for the presence of CO2.

Materials Required:
- Limewater solution (calcium hydroxide dissolved in water)
- Test tube or a clear glass container
- Straw or a tube for blowing air into the solution
- Source of CO2 (such as dry ice or a chemical reaction that produces CO2)

Procedure:
1. Fill a test tube or a clear glass container with limewater solution.
2. Place the test tube or container on a flat surface.
3. Ensure proper ventilation in the area where the experiment is conducted to avoid inhaling excessive CO2.
4. Prepare the source of CO2. If using dry ice, handle it with gloves and place a small piece in a separate container. If using a chemical reaction, ensure it is conducted safely according to the appropriate guidelines.
5. Take a straw or a tube and blow air from your mouth into the limewater solution. This step is essential to remove any CO2 present in the straw or tube itself.
6. Insert the straw or tube into the limewater solution, ensuring that the end is submerged.
7. Gently blow air from the source of CO2 (dry ice or chemical reaction) into the limewater solution through the straw or tube.
8. Observe any changes in the limewater solution.

Observations:
- If CO2 is present in the blown air, it will react with the limewater to form a white precipitate of calcium carbonate (CaCO3). This reaction can be represented as:
CO2 (g) + Ca(OH)2 (aq) → CaCO3 (s) + H2O (l)
- The presence of the white precipitate indicates the presence of CO2 in the chemical reaction.

Conclusion:
By performing this activity and observing the formation of a white precipitate in the limewater solution, we can detect the presence of carbon dioxide in a chemical reaction. This method is simple, cost-effective, and commonly used in various educational and laboratory settings. It allows for a visual confirmation of the presence of CO2, making it an effective tool for identifying the gas in chemical reactions.