Answer:
D) This reaction will be nonspontaneous only at high temperatures.
Explanation:
According the equation of Gibb's free energy -
∆G = ∆H -T∆S
∆G = is the change in gibb's free energy
∆H = is the change in enthalpy
T = temperature
∆S = is the change in entropy .
And , the sign of the ΔG , determines whether the reaction is Spontaneous or non Spontaneous or at equilibrium ,
i.e. ,
if
- ΔG < 0 , the reaction is Spontaneous
- ΔG > 0 , the reaction is non Spontaneous
- ΔG = 0 , the reaction is at equilibrium
The reaction has the value for ∆H = negative , and ∆S = negative ,
Now ,
∆G = ∆H -T∆S
= ( - ∆H ) - T( - ∆S )
= ( - ∆H ) +T( ∆S )
Now, for making the reaction Spontaneous ΔG = negative ,
Hence ,
The temperature is low, then the value for ΔG will be negative , i.e. , Spontaneous reaction .
And , vice versa , at higher temperature , the reaction will have ΔG positive , and the reaction will be non -Spontaneous reaction .
The standard free energy of formation will be zero , only for the compounds that are in their pure form ,
Hence , Al(s) will have ΔG = 0 .
