SOLVED

31) According to the following reaction, how much energy is evolved during the reaction of 32.5 g B2H6 and 72.5 g Cl2? The molar mass of B2H6 is 27.67 g/mol. B2H6(g) + 6 Cl2(g) → 2 BCl3(g) + 6 HCl(g)ΔH°rxn = -1396 kJ A) 1640 kJ B) 238 kJ C) 1430 kJ D) 3070 kJ E) 429 kJ 32) According to the following reaction, how much energy is evolved during the reaction of 0.111 mol B2H6 and 0.252 mol Cl2 (Both gases are initially at STP)? The molar mass of B2H6 is 27.67 g/mol. B2H6(g) + 6 Cl2(g) → 2 BCl3(g) + 6 HCl(g)ΔH°rxn = -1396 kJ A) 58.7 kJ B) 156 kJ C) 215 kJ D) 352 kJ E) 508 kJ 33) According to the following thermochemical equation, what mass of HF (in g) must react in order to produce 345 kJ of energy? Assume excess SiO2. SiO2(s) + 4 HF(g) → SiF4(g) + 2 H2O(l)ΔH°rxn = -184 kJ A) 42.7 g B) 37.5 g C) 150. g D) 107 g E) 173 g 34) Using the following equation for the combustion of octane, calculate the amount of grams of carbon dioxide formed from 100.0 g of octane. The molar mass of octane is 114.33 g/mole. The molar mass of carbon dioxide is 44.0095 g/mole. 2 C8H18 + 25 O2 → 16 CO2 + 18 H2OΔH°rxn = -11018 kJ A) 800.1 g B) 307.9 g C) 260.1 g D) 792.3 g 35) What volume of benzene (C6H6, d= 0.88 g/mL, molar mass = 78.11 g/mol) is required to produce 1.5 × 103 kJ of heat according to the following reaction? 2 C6H6(l) + 15 O2(g) → 12 CO2(g) + 6 H2O(g)ΔH°rxn = -6278 kJ A) 75 mL B) 37 mL C) 21 mL D) 19 mL E) 42 mL 36) Which of the following statements is true? A) State functions do not depend on the path taken to arrive at a particular state. B) DErxn can be determined using constant volume calorimetry. C) Energy is neither created nor destroyed, excluding nuclear reactions. D) ΔHrxn can be determined using constant pressure calorimetry. E) All of the above are true. 37) Two aqueous solutions are both at room temperature and are then mixed in a coffee cup calorimeter. The reaction causes the temperature of the resulting solution to fall below room temperature. Which of the following statements is true? A) The products have a lower potential energy than the reactants. B) This type of experiment will provide data to calculate ΔErxn. C) The reaction is exothermic. D) Energy is leaving the system during reaction. E) None of the above statements are true. 38) A piece of iron (mass = 25.0 g) at 398 K is placed in a styrofoam coffee cup containing 25.0 mL of water at 298 K. Assuming that no heat is lost to the cup or the surroundings, what will the final temperature of the water be? The specific heat capacity of iron = 0.449 J/g°C and water = 4.18 J/g°C. A) 348 K B) 308 K C) 287 K D) 325 K E) 388 K 39) A student is preparing to perform a series of calorimetry experiments. She first wishes to determine the calorimeter constant (Ccal) for her coffee cup calorimeter. She pours a 50.0 mL sample of water at 345 K into the calorimeter containing a 50.0 mL sample of water at 298 K. She carefully records the final temperature of the water as 317 K. What is the value of Ccal for the calorimeter? A) 19 J/K B) 28 J/K C) 99 J/K D) 21 J/K E) 76 J/K 40) A 100.0 mL sample of 0.300 M NaOH is mixed with a 100.0 mL sample of 0.300 M HNO3 in a coffee cup calorimeter. If both solutions were initially at 35.00°C and the temperature of the resulting solution was recorded as 37.00°C, determine the ΔH°rxn (in units of kJ/mol NaOH) for the neutralization reaction between aqueous NaOH and HCl. Assume 1) that no heat is lost to the calorimeter or the surroundings, and 2) that the density and the heat capacity of the resulting solution are the same as water. A) -55.7 kJ/mol NaOH B) -169 kJ/mol NaOH C) -16.7 kJ/mol NaOH D) -27.9 kJ/mol NaOH E) – 34.4 kJ/mol NaOH