1303f18exam2studentkey.pdf - 1 Exam 2 CHEM 1303.001 FALL 2018 KEY Part 1 40 pts SHOW ALL WORK for Part 1 1(10 pts A quantity of 1.44 g of

1303f18exam2studentkey.pdf - 1 Exam 2 CHEM 1303.001 FALL...

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1 Exam 2 CHEM 1303.001 FALL 2018 KEY Part 1. 40 pts SHOW ALL WORK for Part 1. 1. (10 pts) A quantity of 1.44 g of naphthalene (C 10 H 8 , molar mass = 128) was burned in a constant volume bomb calorimeter. Consequently, the temperature of the calorimeter rose from 20.28 to 25.95 °C. If the heat capacity of the bomb (including the water) is 10.2 kJ/°C , calculate the molar heat of combustion of naphthalene (in kJ/mol ). Express the answer in scientific notation. q system = 0 = q reaction + q bomb q reaction = – q bomb q bomb = C bomb (t f – t i ) q bomb = 10.2 kJ (25.95 – 20.28)°C = 10.2 kJ 5.67 °C = 57.83 kJ 1 °C 1 °C D H o combustion = – 57.83 kJ 128 g = – 5,141kJ/mol = – 5.14 x 10 3 kJ/mol 1.44 g 1 mol 2. (4 pts) Write the reaction corresponding the standard enthalpy of formation ( i.e., “the formation reaction”) of C 4 H 4 F 6 ( l ). 4 C( graphite ) + 2 H 2 ( g ) + 3 F 2 ( g ) à C 4 H 4 F 6 ( l ) of C 4 H 6 F 4 ( l ). 4 C( graphite ) + 3 H 2 ( g ) + 2 F 2 ( g ) à C 4 H 6 F 4 ( l ) 3. (14pts) Consider the following balanced REDOX equation in aqueous solution: 16 H + + 2 MnO 4 + 5 C 2 O 4 2– à 2 Mn 2+ + 10 CO 2 + 8 H 2 O The oxidizing agent in this reaction is _________________________. MnO 4 The reducing agent in this reaction is _________________________. C 2 O 4 2– How many mL of 0.760 M K 2 C 2 O 4 are needed to titrate 45.0 mL of 0.300 M Ca(MnO 4 ) 2 ? 0.0450 L Ca(MnO 4 ) 2 0.300 mol Ca(MnO 4 ) 2 2 mol MnO 4 5 mol C 2 O 4 2– 1 mol K 2 C 2 O 4 1 L K 2 C 2 O 4 1 L Ca(MnO 4 ) 2 1 mol Ca(MnO 4 ) 2 2 mol MnO 4 1 mol C 2 O 4 2– 0.760 mol K 2 C 2 O 4 0.0135 mol Ca(MnO 4 ) 2 0.0270 mol MnO 4 0.0675 mol C 2 O 4 2– 0.0675 mol K 2 C 2 O 4 = 0.0888 L K 2 C 2 O 42 = 88.8 mL K 2 C 2 O 4 How many mL of 0.760 M K 2 C 2 O 4 are needed to titrate 35.0 mL of 0.300 M Ca(MnO 4 ) 2 ?
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