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# Ideal Gas Example Problem - Constant Volume

## Worked Chemistry Problems

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

The final pressure of the gas is 1400 mm Hg.