Use satndard enthalpies of formation to calculate standard enthalpies of reaction for the reactions: a) C(graphic) + 2H2O(l) ---> CO2(g) +2H2(g) b) 2CH4(g) + O2(g) ---> 2CO (g) + 4H2(g) c) 2CO(g) + 2Cl2(g) ---> 2COCl2(g) d) Na2SO4 (s) +4CO(g) ---> Na2S(s) +4CO2(g) e) 4HCl(g) + O2(g) ---> 2Cl2(g) + 2H2O(l)