Question

Study the given diagram and answer the following
questions
(a) Write the chemical reaction involved in the
process
(b) Mention the colour of:
1. copper powder and
2. the substance formed after heating it,
(c) How can we reverse the above reaction ? Write
the equation for the reverse reaction and state the
substance that undergoes oxidation and the
substance that undergoes reduction,
(CBSE 2015)
China dish containing
copper powder
Wire gaugo
/
Tripod stand
Bumer​

Answer 1

Solution :

(a) Copper powder upon heating reacts with oxygen (present in air) to form cupric oxide or copper (II) oxide.

2Cu(s)+O2(g)−→heat2CuO(s)Cupric oxide

(b) )(i) Copper powder is brownish in colour.

(ii) The substance formed after heating is cupric oxide. It has black colour.

(c) The reaction can be reversed by heating cupric oxide in a current of hydrogen.

CuO(s)+H2(g)→Cu(s)+H2O(g)

In this reaction, H2 undergoes oxidation to H2O and CuO is reduced to Cu.

I hope it may help you

Answer 2

(a) Copper powder is heated in the presence of air and it forms copper oxide.It's chemical reaction is

2Cu + O₂ -› 2CuO

(b) 1.brown

2.black

(c) It can be reversed by heating CuO with H₂. Its chemical reaction is

CuO + H₂ -› Cu + H₂O

Here CuO undergoes reduction to Cu and H₂O is oxidised to H₂.

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