# Charles’s law (constant pressure) – problems and solutions

1. In a closed container, the gas expands so that the final volume becomes 3 times the initial volume (V = initial volume, T = initial temperature). What is the final temperature?

__Known :__

Initial volume (V_{1}) = V

Final volume (V_{2}) = 3V

Initial temperature (T_{1}) = T

Wanted: Final temperature (T_{2})

__Solution :__

__The formula of Charles’s law :__

The final temperature of gases becomes 3 times the initial temperature.

2. Ideal gases initially have volume V and temperature T. If the gas undergoes the isobaric process so that the temperature becomes 2 times the initial temperature then the final volume of gases is…

__Known :__

Initial volume (V_{1}) = V

Initial temperature (T_{1}) = T

Final temperature (T_{2}) = 2T

__Wanted:__ final volume (V_{2})

__Solution :__

The final volume of gases becomes 2 times the initial volume.

3. In a closed container, ideal gases initially have a volume of 2 liters and temperature of 27^{o}C. If the final volume of gases becomes 3 liters then the final temperature is…

__Known :__

Initial volume (V_{1}) = 2 liters = 2 dm^{3} = 2 x 10^{-3} m^{3}

Final volume (V_{2}) = 3 liters = 3 dm^{3} = 3 x 10^{-3} m^{3}

Initial temperature (T_{1}) = 27^{o}C + 273 = 300 K

__Wanted :__ Final temperature (T_{2})

__Solution :__

The final temperature is 177^{o}C or 177 + 273 = 450 Kelvin.