Law of Gaseous volumes and Avogadro law source : ncerthelp.com source :slideplayer.com

## Law of gaseous volumes-

This law was given by Gay Lussac. According to this law,

#### Ex.1 –

H2      +        Cl2          =     2HCl

1 Vol.              1 vol.               2 vol.

#### Ex.2-

2H2      +        O2          =     2H2O

2 Vol.              1 vol.               2 vol.

#### Ex.3-

N2      +        3H2          =     2 NH3

1 Vol.              3 vol.               2 vol.

### Solution )

H2                +          Cl2         ——->        2 HCl

Volume before reaction        8 litre                        6 litre                              0

Volume  after  reaction        2 litre                        0 litre                              12 litre

Total volume after reaction = volume of H2 left + volume of HCl formed = 2 + 12

#### Volume of reaction mixture = 14 litre Ans.

According to this law,

#### “Equal volumes of gases under similar conditions of pressure and temperatures possess equal number of moles or molecules.”

∝ n         at constant pressure and temperature

∝ N         at constant pressure and temperature

n is  number of moles  and N is  number of  molecules of gases in volume ‘V’ at pressure ‘P’ and temperature ‘T’.