A commercial process for preparing ethanol (ethyl alcohol), C2H5OH, consists of passing ethylene gas, C2H4, and steam over an acid catalyst (to speed up the reaction). The gas-phase reaction is

Estimate ˆ†H for this reaction, using bond energies (Table 9.5).

C-CH-O-HH TABLE 9.5 Bond Energies (in kJ/mol)* Single Bonds 0 H 432 C 4 346 N 386 305 16? 0 459 358 201 142 S 363 272 226 F 565 485 283 190 284 155 CI 428 327 313 218 255 249 240 Br 362 28520 217249 216 190 I295 213 201-- 278 208 175 149 Multiple Bonds - 602 C_N 615 C-0 C C 835 C N 887 C 0 N- 418 N-O 607 S-O (in S02) 532 N N 942 0-0 494 S- (in SO) 469 2 745 (799 in CO2) 1072