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Jennifer Parkinson Tuesday/Thursday (6:30-7:20) GS 226 General Chem 2-CHM 2046 Wednesday/Friday (9:30-10:20) GS 226 jparkinson2020@fau.edu Exam 1 Review: Chapters 5 and 10 1. Which of the following statements is/are incorrect: i. In an endothermic reaction the q for the system is negative while the q for the surroundings is positive. ii. Specific heat is the amount of energy required to raise the temperature of a system 1 degree Celsius. iii. Temperature for calculations for thermodynamics can be in either Kelvin and degrees Celsius. a. i or ii or iii b. i and iii c. i and ii d. ii and iii e. All of the above 2. Which of the following is endothermic? A. Freezing water. B. The formation of rain drops in a storm from a cloud. C. The temperature of a solution increases over a hot plate. D. A gas undergoes sublimation. 3. If a 55g sample of a substance releases has a specific heat of 12.5 J/g*K. It is put out in the snow and its temperature drops 15°C, what amount of energy gained/lost in kJ? 4. When aluminum absorbs 150J of heat, its temperature increases from 12°C to 24°C. If its specific heat capacity is 0.900J/g*K, how many moles are present?

Jennifer Parkinson Tuesday/Thursday (6:30-7:20) GS 226 General Chem 2-CHM 2046 Wednesday/Friday (9:30-10:20) GS 226 jparkinson2020@fau.edu 5. A 100g sample of copper metal at 85°C is placed into an unknown amount of water at 299K in an insulated container at thermal equilibrium. Assuming the calorimeter is perfectly insulated (no heat lost), what is the mass of the water if the final temperature is 42.5 degrees Celsius? (Specific heat of water is 4.184 J/g*K, specific heat of copper is 0.386 J/g*K). 6. A 500mL sample of water at 10°C is mixed with a 500mL sample of water at 75°C. The specific heat capacity of liquid water is 4.184J/g°C. What is the final temperature of the system? 7. If 30g sample of liquid methanol (CH 3 OH) is initially at 25°C, calculate the energy in the form of heat (in kJ) involved when it is heated to a gas at 70°C if the boiling point of CH 3 OH is 64.7°C. (∆H vap = 37.6 kJ/mol, ∆H fus = 3.16 kJ/mol, specific heat gas = 3.62 J/g °C, specific heat liquid = 2.50 J/g °C) 8. A 20 mole sample of liquid nitrogen (N 2 ) at -198°C are boiled to a final temperature of 25°C. If the specific heat capacity is 1.04J/g*C for nitrogen gas and 2.00J/g*C for liquid nitrogen, what is the total amount of energy in the form of heat involved in this reaction? (∆H fus = 0.36 kJ/mol, ∆H vap = 2.79 kJ/mol, boiling point = -195°C).

Jennifer Parkinson Tuesday/Thursday (6:30-7:20) GS 226 General Chem 2-CHM 2046 Wednesday/Friday (9:30-10:20) GS 226 jparkinson2020@fau.edu 9. Find ∆ r H° for the combustion of glucose, 𝐶 6 𝐻 12 ? 6(?) + 6? 2(𝑔) → 6𝐶? 2(𝑔) + 6𝐻 2 ? (?) , using the following standard molar enthalpies of formation: Molecule ∆ f H° (kJ/mol-rxn) 𝐶 6 𝐻 12 ? 6(?) -1274.5 𝐶? 2(𝑔) -393.5 𝐻 2 ? (?) -285.8 10. Find ∆ r H° for the following reaction 2𝐶 (?) + 2𝐻 2(𝑔) + ? 2(𝑔) → 𝐶𝐻 3 𝐶? 2 𝐻 (?) , using the standard molar enthalpies of formation below: Molecule ∆ f H° (kJ/mol-rxn) 𝐶 (?) 1.9 𝐶𝐻 3 𝐶? 2 𝐻 (?) -484.3 11. 𝐻 2(𝑔) + 𝐶? 2(𝑔) = 2𝐻𝐶?(𝑔) Find the enthalpy change for the reaction above using the following information: 1. ?𝐻 3(𝑔) + 𝐻𝐶?(𝑔) → ?𝐻 4 𝐶? (?) 𝛥𝐻 1 = −176.0?𝐽 2. ? 2(𝑔) + 3𝐻 2(𝑔) → 2?𝐻 3(𝑔) 𝛥𝐻 2 = −92.22?𝐽 3. ? 2(𝑔) + 4𝐻 2(𝑔) + 𝐶? 2(𝑔) → 2?𝐻 4 𝐶? (?) 𝛥𝐻 2 = −628.86?𝐽

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