Write the conditions and meaning of the relation q = -W in the light o

1.	Write the conditions and meaning of the relation q = -W in the light of the first law of thermodynamics.
Answer» First law of thermodynamics is stated as ΔE = q + W, if there is no change in the internal energy of the system. ΔE = 0 and the first law of thermodynamics may be written as q = - W .... for ΔE = 0 But - W represents the work done by the system. Therefore, heat absorbed by the system is equal to the work done by the system. The relation q = - W may also be written as W = - q ..... for ΔE = 0 That is, when the energy of the system is kept constant and work is done on the system, then heat must flow from the system to the surroundings.

Write the conditions and meaning of the relation q = -W in the light of the first law of thermodynamics.

Answer»

First law of thermodynamics is stated as ΔE = q + W, if there is no change in the internal energy of the system. ΔE = 0 and the first law of thermodynamics may be written as

q = - W .... for ΔE = 0

But - W represents the work done by the system. Therefore, heat absorbed by the system is equal to the work done by the system. The relation q = - W may also be written as

W = - q ..... for ΔE = 0

That is, when the energy of the system is kept constant and work is done on the system, then heat must flow from the system to the surroundings.

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