Question

why no work is done in free expansion of a gas (in vaccum)? Explain with examples?​

Answer 1

Answer:

P in the expression stands for the pressure against which the gas is expanding. In the case of a free expansion the external pressure is zero hence the work done is zero. another way of looking at it is, work is the transfer of energy between the system and surroundings when there are imbalanced forces between them.

Answer 2

Answer:

When a balloon is ruptured suddenly, or a tyre is

punctured suddenly, the air inside the balloon/

tyre rushes out rapidly to the atmosphere.

This process (expansion of air inside the

balloon/tyre) is so quick that there is no ime for

transfer of heat from the system to the surroundings

or from the surroundings to the system. Such an

adiabatic expansion is called free expansion. It is

characterized by Q = W=0, implying A U=0. Free

expansion is an uncontrolled change and the

system is not in thermodynamic equilibrium. Free

expansion cannot be illustrated ith a P-V

diagram as only the initial state and final state are

known.