# An Ideal gas is sealed within a container at a temperature of 17 degree Celsius and a pressure of 101 KPa. The container is heated until temperature of the gas reaches 100 degree Celsius. A valve in the container is then opened to allow gas to escape until the pressure falls back to 101KPa at 100 degree Celsius.

a) Calculate the pressure in the gas just before the valve is opened.

b) Calculate the fraction of the initial mass of gas that was lost as a result of opening the valve.

## Ti = initial temp = 273+17

Tf = final temp = 273 + 100

initial Pi = 101,000 Pa

final Pf = ? before valve opened

before opening:

P V/nT = R

Pi V/n Ti = Pf V/n Tf

or in other words

Pi/Ti = Pf/Tf

Pf = Pi Tf/Ti

after opening n changes

ni = Pi V/RTi

nf = Pi V/RTf

nf/ni = Ti/Tf

It says fraction lost so 1 - Ti/Tf