Question

Constants Periodic Table Consider the reaction: H2(g) +12(s) + 2HI(g) Average Bond Enthalpies (kJ/mol) Part A Use the bond enthalpies in the table to estimate AH for this reaction, ignoring the fact that iodine is in the solid state. Express your answer in kilojoules to two significant figures. IVO AQ R o 21 ? C-H 413 N-H 391 0-H 463 F-F 155 C-C 348 N-N 163 0-0 146 C=C 614 N-O 201 0=0 495 Cl-F 253 C-N 293 N-F 272 0-F 190 C1-C1 242 C-O 358 N-C1 200 0-ci 203 Br-F 237 C=0 799 N-Br 243 0-I 234 Br-Cl 218 C-F 485 H-H 436 Br-Br 193 C-Cl 328 H-F 567 C-Br 276 H-C1 431 I-C1 208 C-I 240 H-Br 366 I-Br 175 H-I 299 I-I 151 Submit Request Answer Part B Without doing a calculation, predict whether your estimate in Part A is more negative or less negative than the true reaction enthalpy. The actual enthalpy change for the reactants as written will be more exothermic (more negative, smaller) than the value we estimated in Part A. The actual enthalpy change for the reactants as written will be more exothermic (more positive, larger) than the value we estimated in Part A. The actual enthalpy change for the reactants as written will be more endothermic (more positive, larger) than the value we estimated in Part A. The actual enthalpy change for the reactants as written will be more endothermic (more negative, smaller) than the value we estimated in Part A. Submit Request Answer

Answer 1

1 H. H₂ (9) + H₂(g) ) 2 4119) 24 (g), Ahia Bond enthalpy of A I2 15) 20 (9) , Ally Bond enthalpy of I-I = 151 I 2H+ 2 (8) (8) 2 HII AH2 : 2 - 2x Bond enthalpy (9) of Rs H-1 - 2 X 299 - 598 OH OH,t AH₂+AH 436+151-598 9 Some energy is required the for step- Iz 185) - Iz (9) (Enthalpy of sublimation .. we must add this energy to at in part A a id order to get the correct enthalpy change . The actual enthalpy change for the reactants will world be more endothermic (more positive, larger) than the value we estimated in part A " Third statement is correct.

For part C, appendix c is required.