Question
Given the data: Ag_2O_(s), delta H degree_f = -31.1 kJ molF^-1, S degree = +121.3 J mol^-1 K^-1 Ag_(s), Delta H degree_f = 0.00 kJ mol^-1, S degree = +42.55 J mol^-1 K^-1 O_2_(g), Delta H degree_f = 0.00 kJ mol^-1, S degree = + 205.0 J mol^-1 K^-1 Calculate the temperature at which Delta G = 0 for the reaction: Ag_2O_(s) rightarrow 2Ag_(s) + 1/2 O_2(g). Assume that, since the physical states do not change, Delta H degree and Delta S degree are independent of temperature between -50.0 degree C and 950.0 degree C. A. +196 degree C B. +246 degree C C. +423 degree C D. +610 degree C E. all the above F. none of the above
Explanation / Answer
Ag2O(s) -------------> 2Ag(s) + 1/2O2(g)
Delta H = delta H of products - reactants
= [0+0} -[-31.1]
= +31.1 kJ
delta S = s of products - S of reactants
=[2x+42.55 + 1/2x205.0] -(121.3)
=66.3J
The temperature at which delta G = 0 is
T = delta H /delta S
= 31.1x1000/66.3
=460.079 K
= 1960C
Option A