Question

Calculate the approximate kinetic energy of the gas molecules in 82.1 L flask at ${27}^{0}C$ and 2 atm pressure.

• A. 11.67 J
• B. 24.67 J
• C. 24.90 kJ
• D. 78.33 kJ

Answer 1

The correct option is C 24.90 kJ

Given: Volume of gas= $82.1L$

Temperature= ${27}^{0}C$ =298 K

Pressure= $2atm$

Solution: As we know, the ideal gas equation is given by,

$PV=nRT$

where P denotes the pressure,

V denotes the volume

n is the number of moles,

R is the gas constant (0.0821 atm L/K mol or 8.314 J/K mol)

T is the temperature.

So, calculating the number of moles we get,

$n=\frac{PV}{RT}$

On substituting the values we get,

$n=6.71$

Kinetic energy of the gas molecules is given by,

$K=\frac{3nRT}{2}$

On solving we get,

$K=29.40kJ$

Hence, the correct option is (C).