It combines all the three parameters of temperature, pressure and volume.

(P1 V1) /T1= (P2 V2)/T2

Also, Pv = nRT

Where n = number of moles, (R = 0.082 atom dm3 k-1 mol-1).

**Example 1**

If a gas exerts a pressure of 10N/m2 to occupy a volume of 40m3 at 127°C, what will be the volume occupied by pressure of 20N/m2 at 27oc.

**Solution**

(P1 V1) /T1= (P2 V2)/T2

P1 = 10N/m2, V1 = 40m3, T1 = 127°c =273o =400°K

T2 = 27 + 273 = 300oK, P2 = 20N/m2

V2 = (P1 V1 T2)/(p2T1)

= (10 x 40 x 30) / (20 x 400)

= 15m^{3}

**Example 2**

A certain amount of gas occupies 10. 0dm3 at 2 atm and 10oc, Find the number of moles present. (R = 0.082atm dm3 K-1 mol1).

**Solution**

PV = nRT

n = PV/RT

P = 2 atm, V = 10dm^{3 }

10°C = 10 + 273 = 283°K

n = (2 x 10)/(0.082 x 263)

= 0.0862 moles