Experiment. To show that expired air contains carbon dioxide
if you blow air thru a straw into a jar of lime water (CaO), it turns cloudy precipitating CaCO3. https://www.youtube.com/watch?v=xOoutdcV-WI
To conduct an experiment to demonstrate that expired air contains carbon dioxide, you can follow these steps:
Materials needed:
1. Small transparent container or test tube
2. Limewater solution
3. Straw
4. Candle or burning material
Procedure:
1. Prepare the experiment setup by placing a small amount of limewater solution into the transparent container or test tube.
2. Light the candle or burning material and let it burn stably for a few minutes.
3. Take the straw and blow air directly into the limewater solution by exhaling through the straw. Ensure that you do not blow too forcefully to avoid splashing the limewater.
4. Observe any changes occurring in the limewater solution.
Explanation:
When you exhale into the limewater solution, if carbon dioxide is present in your expired air, a chemical reaction occurs. Carbon dioxide reacts with the calcium hydroxide (Ca(OH)2) in the limewater solution, forming a white precipitate called calcium carbonate (CaCO3). This reaction can be represented as follows:
2Ca(OH)2 + CO2 -> CaCO3 + H2O
The presence of the white precipitate indicates that carbon dioxide is present in the expired air and has reacted with the lime water solution. This reaction proves the presence of carbon dioxide in expired air.
It's important to note that this experiment only demonstrates the presence of carbon dioxide and not its exact concentration in expired air. If you need to measure carbon dioxide levels accurately, you will require more precise instruments such as gas analyzers.