Part II. Multiple choice, continued (3 points each). Name:__________________ Please circle your answer. There is only one correct answer to each question. 22. ∆E for a system that releases 12.4 J of heat and does 4.2 J of work on the surroundings is ____________ J. A) 16.6 B) 12.4 C) –8.2 D) –16.6 23. ∆H for an endothermic process is _________ while ∆H for an exothermic process is __________. A) zero, positive B) positive, negative C) negative, zero D) negative, positive 24. The value of ∆H˚ for the reaction below is –283 kJ. Calculate the heat (kJ) released to the surroundings when 12.0 g of CO reacts completely. CO (g) + O2 (g) à CO2 (g) A) 121 B) 660 C) 283 D) 212 25. Given the following reactions N2 (g) + 2O2 (g) à 2NO2 (g) ∆H = 66.4 kJ 2NO (g) + O2 (g) à 2NO2 (g) ∆H = -114.2 kJ the enthalpy of the reaction of nitrogen to produce nitric oxide N2 (g) + O2 (g) à 2NO (g) is __________ kJ. A) 180.6 B) –47.8 C) 47.8 D) –180.6 26. Given the data in the table below, ∆H˚ for the reaction 2CO (g) + O2 (g) à 2CO2 (g) is __________ kJ. Substance ∆Hf˚ (kJ/mol) CO (g) -110.5 CO2 (g) -393.5 CaCO3 (s) -1207.1 A) –677.0 B) 283.3 C) –283.0 D) –566.0
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