Ideal Gas Example Problem - Constant Volume

Worked Chemistry Problems

The ideal gas law applies to real gases at low temperatures.
The ideal gas law applies to real gases at low temperatures. Paul Taylor, Getty Images
Question

The temperature of a sample of an ideal gas confined in a 2.0 L container was raised from 27 °C to 77 °C. If the initial pressure of the gas was 1200 mm Hg, what was the final pressure of the gas?

Solution

Step 1

Convert temperatures from Celsius to Kelvin

K = °C + 273

Initial temperature (Ti): 27 °C

K = 27 + 273
K = 300 Kelvin
Ti = 300 K

Final temperature (Tf): 77 °C

K = 77 + 273
K = 350 Kelvin
Tf = 350 K

Step 2

Using the ideal gas relationship for constant volume, solve for the final pressure (Pf)

Pi / Ti = Pf / Tf

solve for Pf:

Pf = (Pi x Tf) / Ti
Pf = (1200 mm Hg x 350 K) / 300 K
Pf = 420000 / 300
Pf = 1400 mm Hg

Answer

The final pressure of the gas is 1400 mm Hg.