Question

1g of copper powder was taken in a china dish and heated. What change takes place on heating?

When hydrogen gas is passed over this heated substance, a visible change is seen in it.

Give the chemical equation of reactions, the name, and the colour of the products formed in each case.

Answer 1

When 1g of copper powder is taken into a china dish and heated, a black-coloured substance is formed. This substance is a copper oxide(CuO).

$\underset{\mathrm{Copper}}{2\mathrm{Cu}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)\stackrel{∆}{\to }}\underset{\underset{\mathrm{BLACK}}{\mathrm{Copper}\mathrm{oxide}}}{2\mathrm{CuO}\left(\mathrm{s}\right)}$

The Crimson red copper(Cu) is Converted into black Copper oxide(CuO).

When hydrogen gas is passed over this heated Copper Oxide(CuO), copper metal is obtained.

The black-coloured CuO is reduced and brown colour Cu metal is produced.

$\underset{\mathrm{Copper}\mathrm{oxide}}{\mathrm{CuO}\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Copper}}{\mathrm{Cu}\left(\mathrm{s}\right)}+\underset{\mathrm{water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

The black Copper oxide(CuO) is converted into Crimson red copper(Cu).