ENERGY ENTHALPY AND THERMOCHEMISTRY e SiCl 4 l 2 H 2 Ol SiO 2 s 4 HClaq Because

Energy enthalpy and thermochemistry e sicl 4 l 2 h 2

This preview shows page 18 - 20 out of 31 pages.

ENERGY, ENTHALPY, AND THERMOCHEMISTRY e. SiCl 4 (l) + 2 H 2 O(l) SiO 2 (s) + 4 HCl(aq) Because HCl(aq) is H + (aq) + Cl (aq), o f H Δ = 0 - 167 = -167 kJ/mol. Δ H° =     mol kJ 911 mol 1 mol kJ 167 mol 4     mol kJ 286 mol 2 mol kJ 687 mol 1 Δ H° = 1579 kJ ( 1259 kJ) = 320. kJ f. MgO(s) + H 2 O(l) Mg(OH) 2 (s) Δ H° =   mol kJ 925 mol 1     mol kJ 286 mol 1 mol kJ 602 mol 1 Δ H° = 925 kJ ( 888 kJ) = 37 kJ 68. a. 4 NH 3 (g) + 5 O 2 (g) 4 NO(g) + 6 H 2 O(g); Δ H° = o products , f p H Δ n o reactants f, r Δ H n Δ H° =     mol kJ 46 mol 4 mol kJ 242 mol 6 mol kJ . 90 mol 4 = 908 kJ 2 NO(g) + O 2 (g) 2 NO 2 (g) Δ H° = mol kJ . 90 mol 2 mol kJ 34 mol 2 = 112 kJ 3 NO 2 (g) + H 2 O(l) 2 HNO 3 (aq) + NO(g) Δ H° =   mol kJ . 90 mol 1 mol kJ 207 mol 2   mol kJ 286 mol 1 mol kJ 34 mol 3 = 140. kJ b. 12 NH 3 (g) + 15 O 2 (g) 12 NO(g) + 18 H 2 O(g) 12 NO(g) + 6 O 2 (g) 12 NO 2 (g) 12 NO 2 (g) + 4 H 2 O(l) 8 HNO 3 (aq) + 4 NO(g) 4 H 2 O(g) 4 H 2 O(l) _________________________________________________ 12 NH 3 (g) + 21 O 2 (g) 8 HNO 3 (aq) + 4 NO(g) + 14 H 2 O(g) The overall reaction must be exothermic because each step is exothermic.
Image of page 18
CHAPTER 9 ENERGY, ENTHALPY, AND THERMOCHEMISTRY 381 69. 4 Na(s) + O 2 (g) 2 Na 2 O(s), Δ H° = 2 mol   mol kJ 416 = 832 kJ 2 Na(s) + 2 H 2 O(l) 2 NaOH(aq) + H 2 (g) Δ H° =     mol kJ 286 mol 2 mol kJ . 470 mol 2 = 368 kJ 2Na(s) + CO 2 (g) Na 2 O(s) + CO(g) Δ =       mol kJ 5 . 393 mol 1 mol kJ 5 . 110 mol 1 mol kJ 416 mol 1 = 133 kJ In reactions 2 and 3, sodium metal reacts with the "extinguishing agent." Both reactions are exothermic and each reaction produces a flammable gas, H 2 and CO, respectively. 70. 3 Al(s) + 3 NH 4 ClO 4 (s) Al 2 O 3 (s) + AlCl 3 (s) + 3 NO(g) + 6 H 2 O(g) Δ H° =       mol kJ 1676 mol 1 mol kJ 704 mol 1 mol kJ . 90 mol 3 mol kJ 242 mol 6   mol kJ 295 mol 3 = 2677 kJ 71. 5 N 2 O 4 (l) + 4 N 2 H 3 CH 3 (l) 12 H 2 O(g) + 9 N 2 (g) + 4 CO 2 (g) Δ H° =     mol kJ 5 . 393 mol 4 mol kJ 242 mol 12
Image of page 19
Image of page 20

You've reached the end of your free preview.

Want to read all 31 pages?

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture