SOLVED

41) At 1 atm pressure, the heat of sublimation of gallium is 277.0kJ/mol and the heat of vaporization is 271.0 kJ/mol. To the correct number of significant figures, how much heat is required to melt 5.50 mol of gallium at 1 atm pressure? A) 6 kJ B) 33 kJ C) 244 kJ D) 274 kJ 42) According to the following thermochemical equation, what mass of H2O (in g) must form in order to produce 488 kJ of energy? SiO2(s) + 4 HF(g) → SiF4(g) + 2 H2O(l)ΔH°rxn = -184 kJ A) 34.0 g B) 51 g C) 27.1 g D) 95.4 g E) 47.8 g 43) How much heat is absorbed/released when 25.00 g of NH3(g) reacts in the presence of excess (g) to produce NO(g) and H2O(l) according to the following chemical equation? 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(l)ΔH° = 1168 kJ A) 428.6 kJ of heat are absorbed. B) 428.6 kJ of heat are released. C) 1715 kJ of heat are absorbed. D) 1715 kJ of heat are released. 44) How much heat is absorbed when 45.00 g of C(s) reacts in the presence of excess SO2(g) to produce CS2(l) and CO(g) according to the following chemical equation? 5 C(s) + 2 SO2(g) → CS2(l) + 4 CO(g)ΔH° = 239.9 kJ A) 179.8 kJ B) 239.9 kJ C) 898.5 kJ D) 2158 kJ 45) At constant pressure, the combustion of 15.0 g of C2H6(g) releases 777 kJ of heat. What is ΔH for the reaction given below? 2 C2H6(g) + 7 O2(g) → 4 CO2(g) + 6 H2O(l) A) -129 kJ B) -779 kJ C) -1560 kJ D) -3120 kJ 46) When 1.50 mol of CH4(g) reacts with excess Cl2(g) at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written. 2 CH4(g) + 3 Cl2(g) → 2 CHCl3(l) + 3 H2(g)ΔH = ? A) -1420 kJ B) -708 kJ C) +708 kJ D) +1420 kJ 47) Identify what a coffee cup calorimeter measures. A) measures ΔH for aqueous solutions B) measures ΔE for hydrolysis reactions C) measures ΔH for reduction solutions D) measures ΔT for combustion solutions E) measures ΔE for oxidation reactions 48) In the presence of excess oxygen, methane gas burns in a constant-pressure system to yield carbon dioxide and water:             (g) + (g) → (g) + O(l)ΔH = -890.0 kJ Calculate the value of q (kJ) in this exothermic reaction when 1.70 g of methane is combusted at constant pressure. A) -94.6 kJ B) 0.0306 kJ C) -0.0106 kJ D) 32.7 kJ E) -9.46 × 104 kJ 49) Hydrogen peroxide decomposes to water and oxygen at constant pressure by the following reaction: (l) → O(l) + (g)ΔH = -196 kJ Calculate the value of q (kJ) in this exothermic reaction when 4.00 g of hydrogen peroxide decomposes at constant pressure? A) -23.1 kJ B) -11.5 kJ C) -0.0217 kJ D) 1.44 kJ E) -2.31 × 104 kJ 50) When 1.50 g of Ba(s) is added to 100.00 g of water in a container open to the atmosphere, the reaction shown below occurs and the temperature of the resulting solution rises from 22.00°C to 33.10°C. If the specific heat of the solution is 4.18 J/(g ? °C), calculate for the reaction, as written. Ba(s) + 2 H2O(l) → Ba(OH)2(aq) + H2(g) = ? A) -431 kJ B) -3.14 kJ C) +3.14 kJ D