This question can be explained using Gay-Lussac's law which states that:" At constant volume, the pressure of the gas is directly proportional to its temperature in kelvin degree."
This means that:
P = constant*T
For the given problem, since the temperature decreased, then we would expect a decrease in the pressure as well.
Gay-Lussac's law can be rewritten as:
P1 / T1 = P2 / T2 where:
P1 is the initial pressure = 3 atm
T1 is the initial temperature = 30 + 273 = 303 degrees kelvin
P2 is the final pressure that we want to calculate
T2 is the final temperature = -5 + 273 = 268 degrees kelvin
Substitute with the givens in the above equation to get the final pressure as follows:
P1 / T1 = P2 / T2
3 / 303 = P2 / 268
P2 = (3/303) * 268
P2 = 2.65 atm
