NIOS Class 10 Science and Technology Activity 4.7 Chemical Reactions and Equations

This activity 4.7 demonstrates both oxidation and reduction reactions using copper powder and hydrogen gas.

NIOS Class 10 Science and Technology Project File

This activity is based on the NIOS Class 10 Science and Technology chapter 4, 'Chemical Reactions and Equations'.

Aim of the activity

 To observe the oxidation of copper powder and the reduction of copper oxide.

Materials Required

   1. Copper powder

   2. China dish

   3. Spirit lamp or Bunsen burner

   4. Glass tube

   5. Hydrogen gas supply

   6. Test tube holder

Procedure

We take about 2 grams of copper powder in a china dish and heat it over a flame. Now, we observe the change, and then pass hydrogen gas over it, and observe the change again.

Observation

    1.  Reddish-brown copper powder turns black after heating.

    2. The black layer turns brown again when hydrogen gas is passed over it.

Explanation

Copper powder turns black on heating. Copper reacts with oxygen and forms copper oxide (black coloured substance). Copper gains oxygen so it is oxidized.

Oxidation reaction

 `2Cu + O_2\overset{heat}{\rightarrow}2CuO`   

Reduction reaction

`2CuO +H_2\rightarrow 2Cu + H_2O`

CuO is reduced to Cu.

Conclusion

This activity shows the redox reaction (oxidation-reduction).

Frequently Asked Questions

   1. Why does copper powder turn black when heated?

Answer – Copper reacts with oxygen to form black copper oxide.

   2. What is oxidation?

Answer – A chemical reaction in which a substance gains oxygen.

   3. What is reduction?

Answer – A chemical reaction in which a substance loses oxygen.

   4. What is a redox reaction?

Answer- A chemical reaction in which a substance is oxidized and another is reduced, so oxidation and reduction take place simultaneously; this is called a redox reaction.

   5. What happens to hydrogen in this experiment?

Answer- Hydrogen gains oxygen to form water, so it is oxidized.