This activity is about reactions of metals with acids that is from chapter 2 Acids, Bases and Salts.
Aim of the activity
To observe the reaction between zinc and dilute hydrochloric acid and identify the evolving gas
Materials used in the activity
- Test tubes
- Dilute sulphuric acid
- Zinc granules
- Beaker
- Droper
- Soap solution
- Burning candle
- Other acids – HCl, HNO3 ,CH3COOH etc
Caution : This activity needs the teacher’s assistance.
Procedure
We will set the apparatus and take about 2 ml of dilute sulphuric acid in the test tube and add a few pieces of zinc granules to it.
Through the delivery tube , pass the gas evolved to the soap solution and take a burning candle near the bubbles evolving from the soap solution.
We repeat this activity with other acids like HCl, HNO3 and CH3COOH.
Observation
On the surface of zinc granules
We can see tiny bubble on the surface of zinc granules which indicates the reaction between acid and zinc and releasing of a gas.
In the soap solution
When the evolving gas is passed through the solution, the gas filled bubbles are formed.
Near the burning candle
When these gas filled bubbles come in tough with burning candle, they explode with ‘pop sound’
The observations with other acids- HCl,NHO3, CH3COOH
With HCl
Hydorgen gas is produced
Zn + HCl →ZnCl2 + H2
With HNO3
HNO3 produces nitrogen oxides when reacts with zinc
3Zn + 8HNO3 → 3Zn(NO3)2 + 2NO + 4H2O
With CH3COOH
Hydrogen gas is produced in slow speed because acetic acid is a weak acid.
Explanation
When zinc reacts with dilute sulphuric acid, it produces salt zinc sulphate and hydrogen gas.
Zn + H2SO4 → ZnSO4 + H2↑
The hydrogen gas gets filled in the bubbles and rises. When a burning candle come in touch with these bubbles, they explode with pop sound.
This indicates that the evolving gas in the above reaction is ‘hydrogen gas’ because it is an highly inflammable gas.
Conclusion
Zinc metal displaces hydrogen from sulphuric acid and form zinc sulphate and hydrogen gas.
Hydrogen gas is inflammable gas that’s why it burst with pop sound when come in contact with a burning candle.
FAQs
- Why are bubble formed in the soap solution?
Ans.- Hydrogen gas passes through the soap solution and gets rapped in soap solution.
- What happen when acetic acid reacts with zinc granules?
Ans- Acetic acid reacts slowly with zinc but also produces hydrogen gas.