Question

What is the value of AS_surr for the following reaction at 298 K?

6CO_2(g) + 6H₂O_(I) → C₆H₁₂O_6(s)  + 6O_2(g),

ΔG⁰ = 2879 kJ mol^-1,

ΔS⁰ = -210 JK^-1mol^-1.

Answer 1

Given,

6CO_2(g) + 6H₂O_(I) → C₆H₁₂O_6(s)  + 6O_2(g),

ΔG⁰ = 2879 kJ mol^-1,

ΔS⁰ = -210 JK^-1mol^-1

= -0.210 kJ K^-1 mol^-1

T = 298 K ΔH⁰ = ?

ΔG⁰ = ΔH⁰ – TΔS⁰

∴ ΔH⁰ = ΔG⁰ + TΔS⁰

= 2879 + 298(-0.210)

= 2879 – 62.58

= 2816.42 kJ mol^-1

Since ΔH⁰> 0, the reaction is endothermic, and system absorbs heat from surroundings. 

Hence surroundings loses heat,

∴ ΔS⁰surr = -9.45 kJ K^-1