Question

a brown substance X on heating in air forms a substance Y when hydrogen gas is passed over heated why heat again changes back into X

1 name the substance X and Y

2 name the chemical process occering during the 2 changes

3 write the chemical equation

Answer 1

1. X= Cu And Y= CuO
2. Combination reaction and redox reaction. Also exothermic.
3. 2Cu + O2 = 2CuO.
= H2 + CuO = Cu + H2O.
It is because in this reaction copper oxide reduces to copper and hydrogen oxidise to water.