Question

Determine whether the following reaction will be spontaneous or non-spontaneous under standard conditions.

Zn_(s) + Cu²⁺ → Zn²⁺ +Cu_(s) ΔH⁰ = -219 kJ, ΔS⁰ = -21 JK^-1

Answer 1

Given : 

ΔH⁰ = -219 kJ; 

ΔS⁰ = -21 JK^-1 = 0.021 kJ K^-1

ΔG⁰ = ?

For standard conditions : 

Pressure = 1 atm 

Temperature = T = 298 K

ΔG⁰ = ΔH⁰ - TΔS⁰

= -219 – 298 × (-0.021) 

= -219 + 6.258 

= -212.742 kJ

Since ΔG < 0, 

∴ The reaction is spontaneous.