The air we exhale contains carbon dioxide, how?

 

The air we exhale contains carbon dioxide, how?

The air we exhale contains carbon dioxide (CO₂) because of the process of cellular respiration that occurs in our bodies. Here's how it works:

1. Inhalation: When we breathe in, we take in air that contains oxygen (O₂). This oxygen is transported to our cells via the bloodstream.

2. Cellular Respiration: Inside our cells, oxygen is used in a chemical process called cellular respiration. This process breaks down glucose (a sugar) and other nutrients to produce energy that our cells need to function. The basic equation for cellular respiration is:

Glucose + Oxygen → Carbon Dioxide + Water + Energy (ATP)

3. Production of Carbon Dioxide: During this process, carbon dioxide is produced as a waste product. The CO₂ is then carried by the blood from the cells back to the lungs.

4. Exhalation: When we exhale, our lungs expel the carbon dioxide along with some other gases. This is why the air we breathe out contains a higher concentration of carbon dioxide compared to the air we inhale.

So, the carbon dioxide in our exhaled air is a byproduct of the energy production process that happens in our cells.

 

To demonstrate that the air we exhale contains carbon dioxide, you can perform a simple experiment using limewater. Limewater is a clear solution of calcium hydroxide (Ca(OH)₂) that turns milky when it reacts with carbon dioxide. Here’s how you can conduct the experiment:

 

Materials Needed:

- Limewater (can be purchased from a chemical supply store or made by dissolving calcium hydroxide in water)

- A clear glass or jar

- A straw or a piece of tubing

- A small container for the limewater

- A source of exhaled air (your breath)

 

1. Prepare the Limewater:

- If you don’t have limewater ready, you can make it by adding a small amount of calcium hydroxide powder to water. Stir the mixture and let it settle. The clear solution above the sediment is limewater.

 

2. Fill a Container with Limewater:

- Pour some limewater into a clear glass or jar. You don’t need a lot—just enough to cover the bottom of the container.

 

3. Blow Exhaled Air into the Limewater:

- Use the straw or tubing to blow gently into the limewater. Make sure to exhale fully to ensure a steady stream of breath.

 

4. Observe the Reaction:

- As you blow into the limewater, you should observe the solution turning cloudy or milky. This change occurs because the carbon dioxide in your exhaled breath reacts with the calcium hydroxide in the limewater to form calcium carbonate (CaCO₃), which is insoluble in water and causes the milky appearance.

Ca(OH)₂ + CO₂ → CaCO₃ + H₂O

Conclusion:

The cloudiness of the limewater confirms the presence of carbon dioxide in your exhaled breath. This experiment visually demonstrates that we exhale carbon dioxide as a result of the body's metabolic processes.