= 7.7 The bond dissociation energies (in kJ mol"!) for metal hydrides, carbides and oxides are tabulated below. The dissociation energies of the following gas phase molecules are: D(H2) = 434 kJ mol-', D(O2) = 494 kJ mol-', and D(CO) = 1071 kJ mol-?. Metal (M) Fe Ni Pt D(M-H) 287 280 266 D(M-C) 705 666 600 D(M-O) 438 415 320 Use these data to interpret the following observations: (i) H2 and O2 may be dissociatively chemisorbed on all of these metals. (ii) When mixtures of CO and H, are passed over the metals at temperatures of around 500 K, methanol (CH3OH) is produced with Pt (partial reduction of CO) whereas with Ni and Fe the products are hydrocarbon species (C-H and C-C bonds only) and water (complete reduction of CO)