A gas has a pressure of 2.0 atm. If the temperature decreases from 250k to 125k and the volume remains constant, what will be the resulting pressure?

Answer 1

Let's assume that this gas is what's called an "ideal' gas, meaning the gas molecules behave as if they occupy no space, undergo perfectly elastic collisions with one another, and exert no intermolecular forces on one another.

The ideal gas law states that n moles of an ideal gas contained in a volume V at temperature T will exert a predictable pressure P on the container that it occupies.. It could be said in words a variety of ways, but mathematically the law states: PV = nRT were R is a physical constant called the ideal gas constant. In this problem, n and V are also constant.

The first step to solving this question is to solve the gas law for P. Dividing both sides of the equation gives P = nRT/V.

Since we are given the initial pressure, a way to simplify with regards to units is to simply calcualte a ratio P₂/P₁ = (T₂/T₁) = (250/125) = 2. Therefore P₂ = 2(P₁) = 4 atm.