Sample Test 2 (Final)

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  1. The enthalpy change of solution formation for KBr in water is +19.8 kJ/mol. However, the solubility of KBr is very high in water. This is due to:
    1. dipole-dipole attractions.
    2. a higher entropy (disorder) in solution compared to the solid. 
    3. an exothermic solvation process. 
    4. solvent-solvent interactions. 
    5. an endothermic solvation process. 
  2. Which of the following is/are immiscible in water?
    1. CCl4(carbon tetrachloride)
    2. CH3OH (methanol)
    3. C6H6(benzene)
    4. both a and c
    5. all three
  3. Which of the following solutes will produce the largest total molality of solute particles when dissolved in water?a) 2 moles of NaCl
    1. 1 mole of ethanol
    2. 1 mole of Mg(Cl)2
    3. 2 moles of methanol
  4. A 5.50 g sample of a compound is dissolved in 250 grams of benzene solvent. The freezing point of this solution is 1.02° C below that of pure benzene. What is the molar mass of this compound? (Kf for benzene = 5.12° C/molal)
    1. 22.0
    2. 110
    3. 220
    4. 44.0
  5. Calculate the molality of ethanol (CH3CH2OH) in a water solution which is prepared by mixing 39.5 grams of ethanol with 100.0 g of H2O at 20° C.
    1. 0.086 m
    2. 0.094 m
    3. 1.24 m
    4. 8.59 m
  6. A 20.0 gram sample of methanol (CH3OH) was dissolved in 30.0 grams of water. The mole fraction of methanol is:
    1. 0.400
    2. 0.625
    3. 0.728
    4. 0.273
  7. If the vapor pressure of water at 90° C is 0.692 atm, then what is the vapor pressure of a solution (in atm) made by dissoving 1.00 mole of urea in 1.00 kg of water?
    1. 0.692
    2. 0.680
    3. 0.668
    4. 0.656
  8. The colligative property of boiling point elevation is due to:a) osmosis of solute particles.
    1. lowered vapor pressure of solution relative to pure solvent.
    2. ion-dipole interactions.
    3. the chemical nature of the solute.
    4. none of these.
  9. The standard enthalpy of combustion of acetylene (C2H2) is -1410 kJ/mol. How many kJ of heat are liberated by the combustion of 13.0 g of acetylene?
    1. 13 kJ
    2. 705 kJ
    3. 18,326 kJ
    4. 1410 kJ
    5. 780 kJ
  10. The standard enthalpy of formation of CO (g) refers to the DH of which reaction below?
    1. 2 C (graphite) + O2(g) --> 2 CO(g)
    2. C (diamond) + 1/2 O(g) --> CO(g)
    3. C (graphite) + 1/2 O2(g) --> CO(g)
    4. C (graphite) + O2(g) --> CO(g)
  11. Identify the INCORRECT statement below:
    1. Energy is the capacity to do work or transfer heat.
    2. According to the First Law of Thermodynamics, the total amount of energy in the universe is constant.
    3. Endothermic processes require the absorption of energy to occur, corresponding to a positiveDH.
    4. The Gibbs free energy G of a system is increasing in any spontaneous process.
  12. A chemical reaction taking place in a calorimeter causes the temperature to rise 7.5° C. The addition of 50 kJ of energy to the same calorimeter by an electrical heater increases its temperature 2.5° C. What is DH of the chemical reaction?
    1. 16.7 kJ
    2. -16.7 kJ
    3. -150 kJ
    4. 150 kJ

KEY

1)2
2)4
3)1
4)2
5)4
6)4
7)2
8)2
9)2
10)3
11)4
12)3

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