Question

at 300k the pressure inside a gas-filled container is 500 kPa if the pressure inside decreases to 100 kPa but the volume remains the same what is the final temperature of the gas?

Answer 1

Given:

T1 = 300 K
P1 = 500 kPa
P2 = 100 kPa
T2 = ?

Assume that the gas inside the container behaves ideally, we can use the ideal gas equation.

Additional assumption, volume remains constant.

PV = nRT 
P/T = nR/V = constant

P1/T1 = P2/T2

500 kPa / 300 K = 100 kPa / T2
T2 = 60 K