A sample of hydrogen has an initial temperature of 50.° C. When the temperature is lowered to -5.0° C, the volume of hydrogen becomes 212 cm3. What was the initial volume of the hydrogen in dm3?

1 Answer

The initial volume of the gas was 0.255 dm³.

Explanation:

This is an example of Charles' Law.

#V_1/T_1 = V_2/T_2#

#V_1# = ?; #T_1# = (50. + 273.15) K = 323 K

#V_2# = 212 cm³; #T_2# = (-5.0 + 273.15) K = 268.2 K

#V_1 = V_2× T_1/T_2# = 212 cm³ ×#(323"K")/(268.2"K")# = 255 cm³

#V_1# = 255 cm³ × #((1"dm")/(10"cm"))^3# = 0.255 dm³

This makes sense. The initial Kelvin temperature was about 20 % higher than the final temperature. The original volume must also have been about 20 % (40 cm³) larger than the final volume.