An ideal gas in a sealed container has an initial volume of 2.70 L. At constant pressure, it is cooled to 22.00 °C where its final volume is 1.75 L. What was the initial temperature? Solution for an ideal gas PV/T = constant at constant pressure V/T = constant so Vi / Vf = Ti / Tf now Ti = Tf ( Vi / Vf) given Tf = 22 C = 22 + 273 K = 295 K Vi = 2.7 L Vf = 1.75 L plug in the values Ti = 295 K x ( 2.7 L / 1.75 L) Ti = 455.14 K Ti = 455.14 - 273 C Ti = 182.14 C so the initial temperature is 182.14 C .