• The Gibbs equation can be used to calculate whether a reaction is?feasible?or not

ΔG^??= ΔH_reaction^??- TΔS_system^?

• When ΔG^??is?negative, the reaction is?feasible?and likely to occur
• When ΔG^?is?positive, the reaction is?not feasible?and unlikely to occur

Answer

• Step 1:?Calculate ΔS_system^?

ΔS_system^??= ΣΔS_products^??- ΣΔS_reactants^?

ΔS_system^??= (2 x ΔS^??[CaO(s)]) -? (2 x ΔS^??[Ca(s)] + ΔS^??[O₂(g)])

= (2 x 40.00) - (2 x 41.00 + 205.0)

= -207.0 J K^-1?mol^-1

• Step 2:?Convert ΔS^??to kJ K^-1?mol^-1

= -0.207

• Step 3:?Calculate ΔG^?

ΔG^??= ΔH_reaction^??- TΔS_system^?

= -635.5 - (298 x -0.207)

= -573.8 kJ mol^-1

• Step 4:?Determine whether the reaction is feasibleSince the ΔG^??is?negative?the reaction is feasible and likely to occur