Two moles of an ideal gas expand spontaneously into a vacuum. The work done is

Options

(a) 2 joules
(b) 4 joules
(c) zero
(d) infinite

Correct Answer:

zero

Explanation:

In a free expansion , gas is allowed to expand into a vacuum. This happens quickly,so there is no heat transferred. No work is done,because the gas does not displace anything. According to the first law, this means that ΔE initial = 0. There is no change in internal energy, so the temperature stays the same.