Question

how would you prove that hydrogen gas is liberated when zinc is added to the hydrochloric acid.write the balanced chemical reaction

Answer 1

Zn + 2HCl --- ZnCl2 + H2
This is the balanced equation when zinc is added to hydrochloric acid...

♦ Aim : To show the reaction of acids with metals

♦ Apparatus required : 

1. Test tube 
2. Delivery tube 
3. Glass trough 
4. Burner 
5. Soap water 
6. Dil. HCl 
7. Zinc granules.

♦ Procedure : Set the apparatus as shown 

1. Take about 10 ml of dilute HCl in a test tube and add a few zinc granules to it.

2. We will observe the formation of gas bubbles on the surface of zinc granules.

3. Pass the gas being evolved through the soap water.Gas filled bubbles are formed in the soap solution which rise into the air.

4. Bring a burning candle near the gas filled bubbles.

5. The gas present in a soap bubble burns with a ‘pop’ sound.

♦ Chemical Eqn. : 

ZnZn + 2HCl2HCl → ZnCl_2ZnCl2​ + H_2H2​ 

♦ Conclusion : Only ‘hydrogen’ gas burns making a ‘pop’ sound. You will get to know that the hydrogen gas has been liberated.