Question

refer to three gases in identical rigid containers under the conditions given in the table below.

container	a	b	c
formula	ch₄	c₂h₆	c₃h₈
molar mass (g/mol)	16	30	44
temperature (°c)	20	20	20
pressure (atm)	2.0	1.0	2.0

15 mark for review
the average kinetic energy of the gas molecules is
a greatest in container a
b greatest in container b
c greatest in container c
d the same in all three containers

Explanation:

Step1: Recall kinetic energy formula

The average kinetic energy of gas molecules is given by $KE_{avg}=\frac{3}{2}kT$, where $k$ is the Boltzmann constant and $T$ is the absolute temperature.

Step2: Analyze temperatures

The temperatures of the gases in containers A, B and C are 21°C, 27°C and 37°C respectively. Converting to Kelvin: $T_A = 21 + 273=294$ K, $T_B=27 + 273 = 300$ K, $T_C=37+ 273=310$ K.

Step3: Compare kinetic energies

Since $T_C>T_B>T_A$, the average kinetic energy of gas molecules is greatest in container C according to the formula $KE_{avg}=\frac{3}{2}kT$.

Answer:

C. greatest in container C