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Question:

For which of the following processes, ΔS is negative?

N2(g,273K)→N2(g,300K)

C(diamond)→C(graphite)

N2(g,1atm)→N2(g,5atm)

H2(g)→2H(g)

Solution:

(A) When we increase the temperature of a gas then randomness is increased due to kinetic energy gained by molecules. So, ΔS>0
(B) When pressure increases then molecules of gas will come closer and intermolecular distance decreases so entropy will also decrease. and ΔS<0
(C) When Diamond is converted into graphite when it is heated to 1500°C and entropy is increased so ΔS>0
(D) H2 molecule is converted into atoms, So entropy will increase. So ΔS>0