Aim:How is thermodynamic data used to calculate G? QQ:When can an endothermic reaction occur spontaneously? Do Now:What pieces of information do you need to calculate G? Quick Review:Gibbs Free Energy oIf G is (–) the reaction is spontaneous oIf G is (+) the reaction is non-spontaneous Quantitative ThermodynamicsConsider the decomposition of H2O2(hydrogen peroxide) at 298 K and 1 atm pressure according to: 2 H2O2(l) 2 H2O(l) + O2(g)Substance H (kJ/mol) S (J/K mol) H2O2(l) -187.6 109.5 H2O (l) -285.8 69.4 O2(g) 0 205 Find G for the reaction. Calculate H and S for the reaction H = -196.4 kJ S = 124.8 J/K This reaction will be spontaneous! Use Gibb’s Free Energy equation to find G…G = H –TS G = -196.4 –298(0.1248) *don’t forget to convert!G = -196.4 –37.2 G = -233.6 kJ –reaction is spontaneous G can also be calculated the same way as H and S Grxn= nGproducts–nGreactants Consider the decomposition of H
has intentionally blurred sections.
Sign up to view the full version.