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29/09/2021 11:13 am
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The molar heat capacity (Cp) of CD2O is 10 cals at 1000 K. The change in entropy associated with cooling of 32 g of CD2O vapour from 1000 K to 100 K at constant pressure will be: (D = deuterium, atomic mass = 2 u)
(a) 23.03 cal deg–1
(b) -23.03 cal deg–1
(c) 2.303 cal deg–1
(d) -2.303 cal deg–1
1 Answer
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29/09/2021 11:22 am
Correct answer: (b) -23.03 cal deg–1
Explanation:
Given, Cp = 10 cals at 1000 K
T1 = 1000 K. T2 = 100 K
m = 32 g
ΔS = ?
at constant pressure
ΔS = Cp ln\(\frac{T_2}{T_1}\)
= 2.303 x Cp log\(\frac{T_2}{T_1}\)
= 2.303 x 10 log \(\frac{100}{1000}\)
= -23.03 cal deg–1