Chemistry Exam: Thermodynamics and Solutions, Exams of Chemistry

Download Chemistry Exam: Thermodynamics and Solutions and more Exams Chemistry in PDF only on Docsity! Chem 1036 Test 1 February 14, 2011 THIS IS FORM A Name_____________________________ Choose the single best answer to each question. 1. Ethylene glycol has a specific heat capacity of 2.42 J/goC. Calculate q when 3.65 kg of ethylene glycol is cooled from 132C to 85C. A. -1900 kJ B. -420 kJ C. -99 kJ D. -0.42 kJ E. -4.2  10-6 kJ 2. An important step in the synthesis of nitric acid is the conversion of ammonia to nitric oxide. 4NH3(g) + 5O2(g)  4NO(g) + 6H2O(g) Calculate Hrxn for this reaction. Hf [NH3(g)] = -45.9 kJ/mol; Hf [NO(g)] = 90.3 kJ/mol; Hf [H2O(g)] = -241.8 kJ/mol. A. -906.0 kJ B. -197.4 kJ C. -105.6 kJ D. 197.4 kJ E. 906.0 kJ 1 3. The 307 g of an unknown mineral at 98.7C is placed into a calorimeter containing 72.4 g of water at 23.6C. The heat capacity of the calorimeter was 15.7 J/C. The final temperature in the calorimeter was 32.4C. What is the specific heat capacity of the mineral? (c of water is 4.184 J/goC). A. 0.25 J/(g ∙ C) B. 0.18 J/(g ∙ C) C. 0.14 J/(g ∙ C) D. 0.33 J/(g ∙ C) 4. A system absorbs 575 J of heat and does 425 J of work. Calculate the change in the internal energy, E, of the system. A. -150 J B. 150 J C. -1000 J D. 1000 J E. 575 J 5. Using the following data: 2ClF(g) + O2(g) → Cl2O(g) + OF2(g) ∆H° = 167.5 kJ 2 A. liquid A B. liquid B C. liquid C D. liquid D 11. Which of the following statements is incorrect? The more hydroxyl (OH) groups on an alcohol, the more soluble it is in water. The solubility of alcohols in water increases as the number of carbons atoms in the alcohol increases. As lakes heat up, less oxygen can dissolve, which adversely affects fish. Solids usually, but not always, increase their water solubility as the temperature increases. 12. Which of the following ions will be expected to have the most negative heat of hydration, ∆Hhydr? A. Na+ B. Cs+ C. Ca2+ D. Ba2+ E. I¯ 13. Rank the following compounds according to increasing solubility in water. I. CH3-CH2-CH2-CH2-CH3 II. CH3-CH2-O-CH2-CH3 5 III. CH3-CH2-OH IV. CH3OH A. I < III < IV < II B. I < II < IV < III C. III < IV < II < I D. I < II < III < IV 14. Which of the following aqueous liquids will have the lowest freezing point? A. 0.5 m C12H22O11 (sucrose) B. 0.5 m Ca(NO3)2 C. 0.5 m NiSO4 D. 0.5 m Li3PO4 15. Calculate the freezing point of a solution made by dissolving 3.50 g of potassium chloride (molar mass = 74.55 g/mol) in 100.0 g of water. Kf = 1.86C/m. A. -1.7C B. -0.9C C. 0.0C D. 0.9C E. 1.7C 16. A 50.0% by mass solution of sulfuric acid (H2SO4) in water has a density of 1.395 g/mL. What is its molarity? . A. 7.11 M B. 2.32 M 6 C. 1.06 M D. 8.82 M 17. What is the molality of a solution prepared by dissolving 86.9 g of diethyl ether, C4H10O (molar mass = 74.1 g/mol), in 425 g of benzene, C6H6 (molar mass = 78.1 g/mol)? A. 0.362 m B. 0.498 m C. 2.01 m D. 2.76 m 18. Consider a solution that has 7.1 g of KMnO4 (molar mass = 158.0 g/mol) per 100.0 g of water (molar mass = 18.0 g/mol) at 25C. What is the mole fraction of KMnO4 in this solution? A. 0.0080 B. 0.0096 C. 0.066 D. 0.45 7