A gas with a temperature of 21.0°C and a volume of 10.0 L is compressed to 5.00 L. What will be the new temperature?

In order to compute the final volume, we may apply Charle's law, which states that for a given amount of gas at constant pressure, the volume and temperature of that gas are directly proportional. Mathematically, this is written as:

Volume / Temperature = constant

Note that the temperature is measured on the absolute scale whenever applying gas laws. Thus:

10 / (21 + 273) = 5 / (T)

T = 147 K

The new temperature will be 147 K or - 126 °C