Question

2 mole of an ideal gas at 27ºC temperature is expanded
reversibly from 2 lit to 20 lit. Find the entropy change
(R = 2 cal/mol K)
(a) 92.1 (b) 0
(c) 4 (d) 9.2

Answer 1

Explanation:

The correct answer is option d 9.2cal/K

Answer 2

The entropy change  is

(d) 9.2

We know, the change in entropy, ΔS is given as:

ΔS = 2.303*n*R*log (V'/V)

where, n = no. of moles (2)

R = universal gas constant (2 cal/mol K)

V' = Final volume (20L)

V = Initial volume (2L)

So, replacing the volumes in the expression, we get,

ΔS = 2.303*2*2*log (20/2)

= 9.212 log (10)

= 9.212

≈ 9.2

Option (d) is correct.