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This quiz is based on AP Chemistry Enduring understanding: "Energy is neither created nor destroyed, but only transformed from one form to another." It focuses on concepts of energy conservation and calorimetry calculations, including enthalpy of combustion and solution, and the energy of phase changes.
A system absorbs 4500 J in work energy. Its overall internal energy change is +1.5 kJ. Which of the following is the heat change of the system?
4583 J
-3000 J
-4980 J
3000 J
The heat of the solution of ammonium nitrate in water is +25.7 kJ/mol. What is the energy change if 3 moles of ammonium nitrate crystallize out of an aqueous solution?
-25.7 kJ
-77.1 kJ
77.1 kJ
25.7 kJ
A system absorbs 4500 J in work energy. Its overall internal energy change is +1.5 kJ. Which of the following is the heat change of the system?
4583 J
-3000 J
-4980 J
3000 J
11.1 g of calcium chloride is dissolved in 200 g of water at 25 degrees C. The enthalpy of the solution of CaCl2 is -82.8 kJ/mol. What is the final temperature of the water? Assume no heat is lost to the surroundings, and the specific heat of the solution is that of water, 4.18 J/g.degreeC.
39.4 degrees C
34.4 degrees C
34 degrees C
23.09 degrees C
2.00 g of hydrazine (N2H4) is burned in a bomb calorimeter containing 1000 g of water. The temperature changes from 25.0 degrees C to 33.3 degrees C. The C for the calorimeter is 800 J/ degree C and the specific heat of water is 4.18 J/ degree C. What is the molar heat of combustion of hydrazine?
562 kJ/mol
-453 kJ/mol
-662 kJ/mol
662 kJ/mol
True or False, The body at a higher temperature releases heat while the body at a lower temperature absorbs heat. The principle of calorimetry indicates the law of conservation energy, i.e. the total heat lost by the hot body is equal to the total heat gained by the cold body.
True
False
When a 1.000 g sample of the rocket fuel hydrazine, N2H4, is burned in a bomb calorimeter, which contains 1,200 g of water, the temperature rises from 24.62 C to 28.16 C. If the C for the bomb is 840 J/C, calculate Qreaction for combustion of a 1-gram sample.
13.09 KJ
-20.7 kJ
20.7 kJ
-662 kJ
The following acid-base reaction is performed in a coffee cup calorimeter:
H+(aq) + OH-(aq) → H2O(l)
The temperature of 110 g of water rises from 25.0 C to 26.2 C when 0.10 mol of H+ is reacted with 0.10 mol of OH-. Calculate q water
210 J
450 J
550 J
120 J
