At 125 degrees Celsius, the pressure of a sample of He gas is 345 mmHg. At what temperature degrees Celsius will the pressure become 690 mm Hg, if the volume remains constant?

Answer 1

Since V is constant, if the pressure doubles, so does the temperature. Algebraically,

PV=kT
125°C = 398°K

(345)V = k(398)
(690)V = kT

T/398 = 690/345
T = 796°K = 523°C