Question

A 0.5 mol sample of He(g) and a 0.5 mol sample of Ne(g) are placed separately in two 10.0 L rigid containers at 25°C. Each container has a pinhole opening. Which of the gases, He(g) or Ne(g), will escape faster through the pinhole and why?
A) He because the He atoms are moving at a higher average speed than the Ne atoms.
B) Ne because its initial pressure in the container is higher
C) Ne because the Ne atoms have a higher average kinetic energy than the He atoms
D) Both gases will escape at the same rate because the atoms of both gases have the same average kinetic enery

Answer 1

Answer:

A) He because the He atoms are moving at a higher average speed than the Ne atoms.

Explanation:

The expression for the mean speed is:

$C_{avg}=\sqrt {\dfrac{8RT}{\pi M}}$

R is Gas constant having value = 8.314 J / K mol  

M is the molar mass of gas

T is the temperature

Thus, as seen from the formula,  

The average speed of the gas is inversely proportional to the square root of the molar mass of the gas

So, Helium has lower molecular mass than neon and thus, The speed of the sound in helium is greater when compared to that of neon.

Thus, He will escape faster through the pinhole.

Option A. is correct.