Question

A rigid body contains 35 kg of nitrogen at 6 atm . Sufficient quantity of oxygen is supplied to increase the pressure to 9 atm while the temperature remains constant. Amount of oxygen supplied to the tank is

Answer 1

The amount of oxygen added to
increase the pressure from 6 atm
to 9 atm will be 20 kg.
From the gas law we know that:
PV nRT
since VR and T are constant here
> P oc n
since pressure is increased by 1.5
times, hence number of moles
should also increase by 1.5 times
so oxygen added should be equal
to half the number of moles of
nitrogen.
Number of moles of nitrogen in 35
kg- 35000/14 - 2500 moles
Hence number of moles of
oxygen 2500/2 1250 moles
One mole of oxygen weight 16 g
1250 moles of oxygen weight-
1250 x 16 20000 g 20 kg
Hence the amount of oxygen
added to increase the pressure
from 6 atm to 9 atm will be 20 kg.