Aim:to demonstrate that expired air contains carbon dioxide
1-Briefly explain your observations
2- Suggest a suitable control for this demonstration
3 what can be concluded from this experiment
4 labelling experimental set-up
I will be happy to check your thinking. Have you looked at blowing air into limewater?
1- Observations:
To demonstrate that expired air contains carbon dioxide, you can perform a simple experiment. Take a glass or a container with a narrow opening, and fill it with lime water (calcium hydroxide solution). Then, blow into the container through a straw or directly with your mouth for a few seconds. Observe any changes that occur in the lime water.
2- Suitable Control:
In order to have a suitable control for this demonstration, you should perform a parallel experiment with the same conditions and materials, but without blowing into the lime water. This would act as a control to compare the results and determine the influence of blowing into the lime water.
3- Conclusion:
Based on the observations, when you blow into the lime water, you will notice that it turns milky or cloudy. This cloudiness is due to the formation of calcium carbonate as a result of the reaction between carbon dioxide (CO2) in your expired air and the calcium hydroxide (Ca(OH)2) in the lime water. Therefore, this experiment demonstrates that expired air indeed contains carbon dioxide.
4- Labelling Experimental Set-Up:
Label the experimental set-up clearly to communicate the steps and materials used. Here's an example of how you could label the experimental setup:
- Glass/container filled with lime water (calcium hydroxide solution)
- Straw or direct blowing with the mouth
- Blowing into the lime water for a specific duration
- Observation of the changes in lime water (cloudiness/milky appearance)