Question

A certain mass of a gas occupies 2 litres at 27°C and 100 Pa. Find the temperature when volume and pressure become half of their initial values.

Answer 1

V = 2 litres
P = 100 Pa
T = 300 K

T1 = ?

${\displaystyle \text{P}1=\frac{1}{2}\times 100=50\text{Pa}}$

${\displaystyle {\text{V}}_1=\frac{1}{2}\times 2=1 \text{litre}}$

Using gas equation, 

${\displaystyle \frac{\text{PV}}{\text{T}}=\frac{{\text{P}}_1{\text{V}}_1}{{\text{T}}_1}}$ 

${\displaystyle \frac{100\times 2}{300}=\frac{50\times 1}{{\text{T}}_1}}$

${\displaystyle {\text{T}}_1=75\text{K}}$

${\displaystyle {\text{T}}_1=75-273=-198°C}$