Entropy.. can anyone explain me entropy in layman terms?

Question

I just know that Entropy is the unavailable energy..

or difference in the energy

during change of state(say A to B)

wrt "T"

Can you throw more light? Pls?

Answer 1

Some refer to an increase in entropy as an increase in disorganization.  The universe (on average) is becoming more and more disorganized and entropy is increasing.  On a smaller scale, if you have high pressure steam bottled up (in a boiler) it is highly organized.  Allowing the steam to pass through a turbine permits work to be extracted, but the steam becomes less organized (from a higher state to a lower state of organization).  It is possible to calculate the exact amount of work (force x distance) that can be extracted from the steam in a given pressure drop, however nothing is perfect and entropy increases in the expansion process (which is then not reversible).  To restore entropy (or organization) to the steam/condensate, energy must be supplied (furnace) but the entropy of the now larger system (boiler + furnace) must increase.

Answer 2

An increase in entropy in layman terms is the destruction of the universe's potential difference (ability to do work). Imagine the universe is a AA battery connected to an light bulb in a perfectly insulated container (no energy enters or leaves). When it is new, the potential difference is 1.5V and there is ability to do useful things, like make light. As it ages, the voltage eventually dies to 0V, but the light has heated the interior of the container. The energy was conserved, but the potential for doing work is gone. In the real universe, there are hot stars with plenty of fuel to fusion and generate heat and light. Eventually, the universe will face "heat death," or a time when all hydrogen is spent, the stars are all gone, and the universe in one homogeneous distribution of matter and heat. When there is no usable heat differences or mass distribution, the potential to do work is gone.