Activity 4.4 Class 10 Science- Explanation

In this activity, we will learn about the effect of air supply on the nature of flame and understand the complete and incomplete combustion.

Aim of the activity

To observe the different types of flames and understand the conditions for complete and incomplete combustion

Materials Required

    1. Bunsen burner

    2. Gas supply

   3. Matchstick

   4. Metal plate

⚠️ Caution

    1. Perform this activity under teacher’s supervision.

    2. Be careful about gas leakage.

   3. Do not touch the burner while it is hot.

Procedure

We light the Bunsen burner and let the air hole completely closed. Now we observe the colour and nature of the flame.

Now we slowly open the air hole to allow air to mix with the gas and observe the colour and nature of the flame.

Finally, we open the air hole completely to allow more supply of air and observe.

Observation

Explanation

When we burn the burner with air hole closed, it undergoes incomplete combustion because it does not get enough oxygen so produces yellow and sooty flame.

 

When we open air hole completely, enough oxygen mixes with the gas and complete combustion occurs, so the flame is clean and blue.

 

Conclusion

This activity explains that amount of air (oxygen) is responsible for combustion. Insufficient oxygen leads incomplete combustion and sufficient oxygen leads complete combustion.

 

Frequently Asked Questions

    1. Why is the yellow flame smoky?

Answer – Incomplete combustion due to limited oxygen leaves unburnt carbon.

   2. Which flame is hotter yellow or blue?

Answer – Blue flame is hotter because of complete combustion, produces more heat.