If a sample of gas is at 672 °C and 3.9 atm, what is the new temperature at 12.2 atm?

In order to calculate the final temperature of the gas, we may apply Charles's law, which states that the pressure and temperature of a fixed amount of gas at constant volume are directly proportional. Mathematically:

P/T = constant

(absolute temperature is used, so T = 672 + 273 = 945 K)

Thus,

3.9 / 945 = 12.2 / T

T = 2,956 K or 2,683 °C