What happen to the internal energy of a gas during (i) isothermal exp

1.	What happen to the internal energy of a gas during (i) isothermal expansion (ii) adiabatic Expansion?
Answer» (i) In isothermal expansion ,temperature remains constant.Therefore internal energy which is a function of temperature will remain constant. (ii)for adiabatic change dQ = 0 and hence first law of thermodynamics becomes 0 = dU + dW dW = - dU During expansion, work is done by the gas i.e. dW is positive. Hence ,dU must be negative. Thus ,in an adiabatic expansion , the internal energy of the system will decrease.

What happen to the internal energy of a gas during (i) isothermal expansion (ii) adiabatic Expansion?

Answer»

(i) In isothermal expansion ,temperature remains constant.Therefore internal energy which is a function of temperature will remain constant.

(ii)for adiabatic change dQ = 0 and hence first law of thermodynamics becomes

0 = dU + dW

dW = - dU

During expansion, work is done by the gas i.e. dW is positive. Hence ,dU must be negative.

Thus ,in an adiabatic expansion , the internal energy of the system will decrease.

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What happen to the internal energy of a gas during (i) isothermal expansion (ii) adiabatic Expansion?

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