Question

Calculate the temperature (in ºC) to which silver ore, Ag2O, must be heated to spontaneously decompose the ore to oxygen gas and solid silver metal at standard state. (ΔHºf of Ag2O(s) = –31.05 kJ/mol; Sº values: Ag(s), 42.55 J/mol•K; O2(g), 205.1 J/mol•K; Ag2O(s), 121.3 J/mol•K)
A. 374 ºC
B. 234 ºC
C. 467 ºC
D. 195 ºC
E. 843 ºC

Answer 1

2Ag2O ==> 4Ag + O2

dHorxn = (n*dHo products) - (n*dHo reactants).
dSorxn = (n*dSo products) - (n*dSo readctants)
dGorxn = dHorxn - TdSorxn

Substitute dHo and dSo from above, set dGo = 0 and solve for T (in kelvin) then convert to C.

Answer 2

Ok for dHorxn I got 62.1kJ
for dSorxn I got 132.7JK

I did 62.1kJ x1000 to make it JK units too.

So i got

0=62100-(T)(132.7)
so T = 195degrees right?

Answer 3

I worked this a day or so ago and I think that's what I had.

Answer 4

Ok thanks!