Name: All About Air Pollution
Uploaded: 2019-07-19
Duration: 5 min 20 s
Description: Air pollution is a primary concern worldwide because it harms organisms and the environment. Explore the various methods to curb it.

Question

Describe an experiment to find the % of oxygen in air.

Accepted Answer

Measuring the percentage of oxygen in the air:

The apparatus: A tube of hard glass is connected to two gas syringes A and B. The tube is packed with small pieces of copper wire. At the start, syringe A contains $100 {cm}^{3}$ air. B is empty.

These are the steps:

Heat the tube containing copper using a Bunsen burner. Then push in A's plunger, as shown above. This forces the air into B. When A is empty, push in B's plunger, forcing the air back to A. Repeat several times. As the air is pushed to and fro, the oxygen in it reacts with the hot copper, turning it black.

Stop heating the tube after about $3$ minutes, and allow the apparatus to cool. Then push all the gas into one syringe and measure its volume. (It is now less than $100 {cm}^{3}$ .)

Repeat steps $1 and 2$ until the volume of the gas remain steady. This means all the oxygen has been used up. Note the final volume.

The results Starting volume of air: $100 {cm}^{3}$ . The final volume of air: $79 {cm}^{3}$ .

So the volume of oxygen in $100 {cm}^{3}$ the air is $21 {cm}^{3}$ .

The percentage of oxygen in the air is therefore $\frac{21}{100} \times 100 = 21 % .$

Describe an experiment to find the % of oxygen in air.

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