JEE Main2014ChemistryThermodynamics (C)Actual
The molar heat capacity ( C _ p ) of CD ₂ O is 10 cals at 1000 ~K . The change in entropy associated with cooling of 32 ~g of CD ₂ O vapour from 1000 ~K to 100 ~K at constant pressure will be: ( D = deuterium, atomic mass =2 u )
Options
- A23.03 cal deg ⁻¹
- B-23.03 cal deg ⁻¹
- C2.303 cal deg ⁻¹
- D-2.303 cal deg ⁻¹
Correct answer
B. -23.03 cal deg ⁻¹
Step-by-step solution
Given, C_p=10 cals at 1000 ~K aligned &T₁=1000 ~K . T₂=100 ~K &m=32 ~g aligned S=? at constant pressure aligned & S=C_p T₂ T₁ &=2.303 C_p T₂ T₁ &=2.303 10 100 1000 &=-23.03 cal deg ⁻¹ aligned