41. When 0.500 g of cyclohexane, C6H12, is combusted in a bombcalorimeter that has a water sheath containing 750.0 g of water,the temperature of the water increased by 5.5 °C. Assuming that thespecific heat of water is 4.18 J/(g °C), and that the heatabsorption by the calorimeter is negligible, calculate the enthalpyof combustion per mole of cyclohexane.

   (A). 2.90 x 106 J/mol

   (B). 4.20 x 106 J/mol

   (C). 1.19 x 104 J/mol

   (D). 2.97 x 105 J/mol

   (E). 8.21 x 106 J/mol

42. Choose the reaction that illustrates ΔH°f for Ca(NO3)2.

   (A). Ca(s) + N2(g) + 3O2(g)  Ca(NO3)2 (s)

   (B). Ca+(aq) + NO3-(aq)  Ca(NO3)2 (s)

   (C). Ca+(s) + NO3(aq)  Ca(NO3)2 (s)

   (D). Ca(s) + N2(g) + O2(g)  Ca(NO3)2 (s)

   (E). 2Ca(s) + 2N2(g) + 3O2(g)  Ca(NO3)2 (s)

45. Give the equation with the elements in Na2SO4 in theirstandard state as the reactants and Na2SO4 as the product.

   (A). 2 Na(s) + 1/8 S8 (s, rhombic) + 2 O2(g) Na2SO4

   (B). Na(s) + S8 (s, rhombic) + 2 O2(g)  Na2SO4

   (C). Na(s) + S (s, rhombic) + ½ O2(g)  NaSO

   (D). Na(s) + 1/8 S8 (s, rhombic) + 2O2(g) NaSO4

46. A gas cylinder contains 10.0 kg of C3H8 (propane) gas.Calculate the heat associated with the complete combustion of allof the propane in the cylinder. MW of C3H8 is 44.10 g/mol.

C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(g) Δrxn = -2044 kJ

   (A). -5.68 x 105 kJ

   (B). -4.63 x 105 kJ

   (C). +5.68 x 105 kJ

   (D). +4.63 x 105 kJ

   (E). 2.31 x 105 kJ

48. Use the Δof information provided to calculate Δorxn for thefollowing reaction:

SO2Cl2(g) + 2H2O(l)  2HCl(g) + H2SO4(l) Δorxn = ?

Δof (kJ/mol)

SO2Cl2(g) -364

H2O(l) -286

HCl(g) -92

H2SO4(l) -814

49. Calculate the change in internal energy (Δ) for a systemthat is giving off 26.0 kJ of heat and is changing from 12.00 L to6.00 L in volume at 1.50 atm pressure. (101.3 J = 1 L∙tm)

50. Use bond energies to calculate the Δrxn for the followingreaction:

N2(g) + 3H2(g)  2NH3(g) (balanced?)

51. Which of the following (with specific heat capacityprovided) would show the smallest temperature change upon gaining155 J of heat?

   (A) 25.0 g Au, CAu = 0.128 J/g.°C

   (B) 25.0 g Ag, CAg = 0.235 J/g.°C

   (C) 50.0 g Al, CAl = 0.903 J/g.°C

   (D) 50.0 g Cu, CCu = 0.385 J/g.°C

   (E) 25.0 g granite, Cgranite = 0.790 J/g°C

52. Use the standard reaction enthalpies given below todetermine ΔHorxn for the following reaction:

2 NO(g) + O2(g)  2 NO2(g) Δorxn = ?

Given:

N2(g) + O2(g)  2 NO(g) Δorxn = +183 kJ

½ N2(g) + O2(g)  NO2(g) Δorxn = +33 kJ

   (A) -211 kJ

   (B) -117 kJ

   (C) -153 kJ

   (D) +165 kJ

   (E) +795 kJ