Chemistry question help

Question

The temperature of a sample of iodine gas at 74.7 kPa is changed, causing a change in volume from 130.9 L to 62.9 L. If the starting temperature was 15.6 °C, and its new pressure is now 1.3 atm, what is the final temperature in degrees Celsius?

Answer value

Answer 1

From the ideal gas law, P₁V₁ /P₂V₂ = nRT₁ /nRT₂ which, for the same amount of gas, can be re-written as T₂ = P₂V₂T₁ / P₁V₁ for the current example. First we convert one of the pressures, e.g. P₂ = 1.3 atm (101.3 kPa/ 1 atm) = 131.7 kPa, and convert T₁ to 288.6 Kelvin.

T₂ = (131.7)(62.9)(288.6) /[(74.7)(130.9)] = 244 K = -29 °C.