JEE Main2014ChemistryThermodynamics (C)Actual
The ( S ^ ) of the following substances are: . CH ₄ ~g ) 186.2 JK ⁻¹ ~mol ⁻¹ O ₂ (g) 205.2 JK ⁻¹ ~mol ⁻¹ CO ₂( ~g ) 213.6 JK ⁻¹ ~mol ⁻¹ H ₂ O ( g ) 69.9.JK ⁻¹ ~mol ⁻¹ The entropy change ( S ^ ) for the reaction CH ₄( ~g )+2 O ₂( ~g ) CO ₂( ~g )+2 H ₂ O (l) is:
Options
- A-312.5 ~J ~K ⁻¹ ~mol ⁻¹
- B-242.8 JK ⁻¹ ~mol ⁻¹
- C-108.1 JK ⁻¹ ~mol ⁻¹
- D-37.6 ~J ~K ⁻¹ ~mol ⁻¹
Correct answer
B. -242.8 JK ⁻¹ ~mol ⁻¹
Step-by-step solution
S ^ = S ^ _ CO ₂ +2 S ^ _ H ₂ O - ( S ^ CH ₄+2 S _ O ₂ ^ )=(213.6+2 69.9)-(186.2+2 205.2)=-242.8 ~J ~K ⁻¹ ~mol ⁻¹