# 2 mole of an ideal gas at 27 degree celcius and 1 atm pressure expand isothermally and reversibly till its pressure becomes 0.25 atm . calculate q , w and delta u

T = 273 + 27 = 300K and n = 2

$W=-2.303nRT\mathrm{log}\frac{{p}_{1}}{{p}_{2}}\phantom{\rule{0ex}{0ex}}=-2.303\times 2\times 0.082\times 300\times \mathrm{log}\frac{1}{0.25}\phantom{\rule{0ex}{0ex}}=-68.21J$

At constant temperature,

ΔU = 0 (First law of thermodyanamics, ΔU = q + W,and for irreversible process q=-W)

and,

W= -q = 68.21J

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