Explain physical and chemical properties of copper.

Physical properties: Copper is a reddish-brown metal, highly lustrous, high density and high melting point (${1356}^{\circ }C$).

Chemical properties:

1. Action of Air and Moisture: Copper gets covered with a green layer of basic copper carbonate in the presence of $C{O}_2$ and moisture.

$2Cu+O_2+C{O}_2+H_{2}O\to CuC{O}_3.Cu(OH{)}_2$

2. Action of Heat: On heating at different temperatures in the presence of oxygen, copper forms two types of oxides CuO and $C{u}_{2}O$.

$2Cu+O_2\stackrel{below1370K}{\to }2CuO$ (copper II oxide –black)

$4Cu+O_2\stackrel{above1370K}{\to }2C{u}_{2}O$ (copper I oxide-red)

3. Action of Acids:

With dil.HCl and dil.$H_{2}S{O}_4$: Dilute acids such as HCl and $H_{2}S{O}_4$ have no action on these metals in the absence of air. Copper dissolves in these acids in the presence of air.

$2Cu+4HCl+O_2\left(air\right)\to 2CuC{l}_2+2H_{2}O$

$2Cu+2H_{2}S{O}_4+O_2\left(air\right)\to 2CuS{O}_4+2H_{2}O$

With dil.HNO₃: Copper reacts with dil.HNO₃ to liberate Nitric Oxide gas.

$3Cu+8HN{O}_3\left(dil\right)\to 3Cu(N{O}_3{)}_2+2NO\uparrow +4H_{2}O$

With conc.HNO₃ and conc.$H_{2}S{O}_4$: Copper reacts with conc. $HN{O}_3$ and conc.$H_{2}S{O}_4$ to liberate nitrogen dioxide and sulphur dioxide respectively.

$Cu+\underset{conc.}{4HN{O}_3}\to Cu(N{O}_3{)}_2+2N{O}_2\uparrow +2H_{2}O$

$Cu+\underset{conc.}{2H_{2}S{O}_4}\to CuS{O}_4+S{O}_2\uparrow +2H_{2}O$

4. Action of Chlorine: Chlorine reacts with copper, resulting in the formation of copper (II) chloride.

$Cu+C{l}_2\to CuC{l}_2$

5. Action of Alkalis: Copper cannot be attacked by alkalis.