Consider the following reaction:

Question

CaCO3(s)→CaO(s)+CO2(g).
Estimate ΔG∘ for this reaction at each of the following temperatures. (Assume that ΔH∘ and ΔS∘ do not change too much within the given temperature range.)

A) 310K
B) 1070K
C) 1470K

And is A,B,C spontaneous or non spontaneous?

Answer 1

dHorxn = (n*dHoformation producs) - (n*dHoreactants)

dSo rxn = (n*dSo formation products( - (n*dSo formation reactants)

dGrxn = dHrxn - TdSrxn
dG<0 spontaneous
dG=0 equilibrium
dG>0 not spontaneous.

Answer 2

Im still confused..

is n 2?

and if so would it look like this for A

dHorxn=(2*2.84)-(2*-.227)??

Answer 3

n stands for number of mols. It is 1 for CaO, 1 for CaCO3, and 1 for CO2.
Look up dHo formation CO2, CaO, and CaCO3. Calculate dHo reaction.

Look up dSo for CO2, CaO, and CaCO3. Calculate dSo reaction.

Then dGorxn = dHorxn - TdSorxn