References t6-3 hess's law for the reaction: agi(s) + br2(g) → agbr(s) + i2(s), δh° = –54.0 kj δhf° for agbr(s) = –100.4 kj/mol δhf° for br2(g) = +30.9 kj/mol the value of δhf° for agi(s) is:

H + Br > HBr let, H2 + Br2 > 2HBr delta H = -72 kj(1) H2 > 2H ...delta H = 436 kj(2) Br2 > 2Br delta H = 224 kj (3) subtracting (2) from (1)... H2 + Br2 - H2 > 2HBr - 2H delta H = -72-436 = -508 kj Br2 + 2H > 2HBr delta H = -508 kj (4) subtracting (3) from (4)... Br2 + 2H - Br2 > 2HBr - 2Br deltaH = -508 - 224 = -732 kj 2H + 2Br > 2HBr delta H = -732 kj dividing it by 2... H + Br > HBr delta H = -732/2 = -366 kj so the delta H for the reaction is -366 kj ... let, Fe2O3 + 3CO > 2Fe + 3CO2 ...delta H = -24.8 kj(1) 2CO + O2 > 2CO2 delta H = -566 kj(2) multiplying (1) by 2... 2Fe2O3 + 6CO > 4Fe + 6CO2 ...delta H = -24.8 X 2 = -49.6 kj (3) multiplying (2) by 3... 6CO + 3O2 > 6CO2 delta H = -566 X 3 = -1698 kj(4) subtracting (3) from (4)... 6CO + 3O2 - ( 2Fe2O3 + 6CO) > 6CO2 - ( 4Fe + 6CO2) ...delta H = -1698 - -49.6 = -1698 + 49.6 = -1648.4 kj 6CO + 3O2 - 2Fe2O3 - 6CO > 6CO2 -4Fe - 6CO2 ...delta H = -1648.4 kj 3O2 - 2Fe2O3 > -4Fe...delta H = -1648.4 kj 4Fe + 3O2 > 2Fe2O3 delta H = -1648.4 kj

Cr(oh)3 -> cr(3+) + 3oh-