Question

The average molecular speed in a sample of Ar gas at a certain temperature is 391 m/s. The average molecular speed in a sample of Ne gas is ______ m/s at the same temperature.

Answer 1

Answer:

550 m/s

Explanation:

The average molecular speed (v) is the speed associated with a group of molecules on average. We can calculate it using the following expression.

$v = \sqrt{\frac{3 \times R \times T}{M} }$

where,

• R: ideal gas constant

• T: absolute temperature

• M: molar mass of the gas

We can use the info of argon to calculate the temperature for both samples.

$T = \frac{v^{2} \times M}{3 \times R} = \frac{(391m/s)^{2} \times 39.95g/mol}{3 \times 8.314J/k.mol} = 2.45 \times 10^{5} K$

Now, we can use the same expression to find the average molecular speed in a sample of Ne gas.

$v = \sqrt{\frac{3 \times R \times T}{M} } = \sqrt{\frac{3 \times (8.314J/k.mol) \times 2.45 \times 10^{5}K }{20.18g/mol} } = 550 m/s$