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