sampletest2

Version 1 by Jason T Hardy
on Aug 29, 2007 03:30.

compared with
Key
This line was removed.
This word was removed. This word was added.
This line was added.

Changes (62)

View Page History
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:a) dipole-dipole attractions.
## dipole-dipole attractions.
b) ## a higher entropy (disorder) in solution compared to the solid. 
c) an exothermic solvation process.
d) solvent-solvent interactions.
e) an endothermic solvation process.
2. Which of the following is/are immiscible in water? a) CCl4(carbon tetrachloride)
## an exothermic solvation process. 
## solvent-solvent interactions. 
## an endothermic solvation process. 
# Which of the following is/are immiscible in water?
## CCl4(carbon tetrachloride)
b) ## CH3OH (methanol)
c) ## C6H6(benzene)
d) ## both a and c
e) ## 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
b) ## 1 mole of ethanol
c) ## 1 mole of Mg(Cl)2
d) ## 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? (K{~}f~ for benzene = 5.12° C/molal)a) 22.0
## 22.0
b) ## 110
c) ## 220
d) ## 44.0
5. # Calculate the molality of ethanol (CH{~}3{~}CH{~}2{~}OH) in a water solution which is prepared by mixing 39.5 grams of ethanol with 100.0 g of H{~}2{~}O at 20° C.a) 0.086 m
## 0.086 m
b) ## 0.094 m
c) ## 1.24 m
d) ## 8.59 m
6. # A 20.0 gram sample of methanol (CH{~}3{~}OH) was dissolved in 30.0 grams of water. The mole fraction of methanol is:a) 0.400
## 0.400
b) ## 0.625
c) ## 0.728
d) ## 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? a) 0.692
## 0.692
b) ## 0.680
c) ## 0.668
d) ## 0.656
8. # The colligative property of boiling point elevation is due to:a) osmosis of solute particles.
b) ## lowered vapor pressure of solution relative to pure solvent.
c) ## ion-dipole interactions.
d) ## the chemical nature of the solute.
e) ## none of these.
9. # The standard enthalpy of combustion of acetylene (C{~}2{~}H{~}2~) is \-1410 kJ/mol. How many kJ of heat are liberated by the combustion of 13.0 g of acetylene?a) 13 kJ
## 13 kJ
b) ## 705 kJ
c) ## 18,326 kJ
d) ## 1410 kJ
e) ## 780 kJ
10. The standard enthalpy of formation of CO (g) refers to the DH of which reaction below?a) 2 C (graphite) + O2(g) --> 2 CO(g)
# The standard enthalpy of formation of CO (g) refers to the DH of which reaction below?
## 2 C (graphite) + O2(g) \--> 2 CO(g)
b) ## C (diamond) + 1/2 O(g) \--> CO(g)
c) ## C (graphite) + 1/2 O2(g) \--> CO(g)
d) C (graphite) + O2(g) --> CO(g)
## C (graphite) + O2(g) \--> CO(g)
# Identify the *INCORRECT* statement below:
11. Identify the *INCORRECT* statement below:a) ## Energy is the capacity to do work or transfer heat.
b) ## According to the First Law of Thermodynamics, the total amount of energy in the universe is constant.
c) ## Endothermic processes require the absorption of energy to occur, corresponding to a positiveDH.
d) ## 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?a) 16.7 kJ
b) -16.7 kJ
c) -150 kJ
## 16.7 kJ
## \-16.7 kJ
## \-150 kJ
d) ## 150 kJ
13. Given the following thermodynamic data at 25° C:2 HCl(g) + F2(g) --> 2 HF(l) + Cl2(g);DH° = -988 kJ/mol
H2(g) + F2(g) --> 2 HF(l);DH° = -1200 kJ/mol
2 H2(g) + O2(g) --> 2 H2O(l);DH° = -572 kJ/mol
Calculate theDH° of the following reaction: 4HCl(g) + O2(g) --> 2 H2O(l) + 2 Cl2(g)
a) -148 kJ/mol
b) 996 kJ/mol
c) -3748 kJ/mol
d) -2760 kJ/mol
14. In which of the following processes is the system entropy decreasing?a) expansion of gas
b) dissolving of NaCl in water
c) vaporization of CCl4
d) condensation of water
15. If the entropy of the universe is increasing in any spontaneous process, how can salts crystallize out of solution, a process which causes a greater ordering of the particles?a) The entropy of a system can decrease during a spontaneous process if the entropy of the surroundings is increasing even more.
b) The crystallization process is a paradoxical violation of the Second Law of Thermodynamics, since the latter is only an approximation.
c) Crystalline salts have a higher entropy than their solutions.
d) Crystallization processes always have a positiveDG.
16. Consider the following reaction at 50° C, given DH° = \-57.2 kJ/mol and DS° = \-175.8 J/mol-k :2 NO2(g) --> N2O4(g)a) This reaction is nonspontaneous at 50° C, but could be made spontaneous at sufficiently high T.
b) This reaction is nonspontaneous at 50° C, but could be made spontaneous at sufficiently low T.
c) This reaction is spontaneous at these conditions, but could be made nonspontaneous by increasing the T.
d) This reaction is spontaneous at these conditions, but could be made nonspontaneous by decreasing the T.
e) This reaction is spontaneous under all temperature conditions.
17. For the reaction 2 NO + Br{~}2~ \--> 2 NOBr{~}2~ the rate of reaction could be expressed as:a) (-2/1)(D[NOBr2]/Dt)
b) (-1/2)(D[NOBr2]/Dt)
c) (+1/2)(D[NOBr2]/Dt)
d) (+1/1)(D[NOBr2]/Dt)
e) (+2/1)(D[NOBr2]/Dt)
18. A reaction A \-----> products, is first order in A with a rate constant of 0.33 min^\-1^. How many minutes will it take for a concentration of A of 0.13 M to decrease to 0.088 M by this reaction? a) 1.2
b) 1.4
c) 0.70
d) 0.13
e) none of these
19. A reaction has a rate law of: rate = k \[ClO{~}3{~}^\-^\] \[Cl^\-^\] \[H^+^\]^2^. If the initial reaction rate is 3.2 x 10^\-3^ M/s, then what is the rate constant if the initial concentrations are \[ClO{~}3{~}^\-^\]~o~= 0.10 M, \[Cl^\-^\]~o~= 0.10 M, \[H^+^\]~o~= 0.20 M? (units are M^\- 3^ x s^\-1^)a) 1.6
b) 8.0
c) 1.2
d) 0.62
e) none of these
20. The data for the reaction, 2 NO + Cl{~}2~ \----> 2 NOCl{~}2~ , is given: experiment # [NO] [Cl2] initial rate M/s

(1) 0.0010 0.0020 3.55 x 10-3
(2) 0.0010 0.0040 1.42 x 10-2
(3) 0.0020 0.0040 2.84 x 10-2
The reaction is:a) zero order in both [NO] and [Cl2]
b) 1st order in [NO], 1st order in [Cl2] , 2nd order overall
c) 1st order in [NO], 2nd order in [Cl2], 3rd order overall
d) 2nd order in [NO], 1st order in [Cl2], 3rd order overall
e) 2nd order in [NO], 2nd order in [Cl2], 2nd order overall

21. What is the rate constant for a first order reaction A \-----> B given the following data: Time (s) [A]
-----------------
0 1.76
6 0.88
12 0.44
18 0.22
a) 0.23
b) 1.0
c) 0.17
d) 0.12
e) can't be determined
22. Which of the following statements about catalysts is *NOT TRUE?* a) Enzymes are biological catalysts.
b) They can be in a different phase from the reactants.
c) They often provide a different reaction pathway for the reaction.
d) They lower the activation energy of a chemical reaction.
e) They are the same as intermediates.
23. The reaction A + B \-----> C + D, obeys the rate law: Rate= k\[A\]\[B\]. Which response lists all the proposed mechanisms that are *CONSISTENT* with this information and none that are inconsistent?I. A + B -----> C + D (one step)
II. A + B <-----> E (fast, equilibrium); E -----> C + D (slow)
III. A + B <-----> E (fast, equilibrium); A + E <-----> C + B (slow)
a) I and II
b) II
c) III
d) II and III
e) I, II, and III

24. The gas phase reaction X + Y \-----> Z has a reaction rate which is experimentally observed to follow the realationship of Rate = k\[X\]^2^\[Y\]. If the concentration of X is tripled and the concentration of Y is doubled, the reaction rate would be increased by a factor of:a) 6
b) 9
c) 12
d) 18
e) 36
25. Consider the following equilibrium in which all components are gases at 2000° C: 2SO{~}2~ + O{~}2~ <-----> 2SO{~}3~. Suppose that 10.0 mol SO{~}2~ and 8.0 mol O{~}2~ are introduced into a 1 L container and allowed to come to equilibrium. After sufficient time to reach the equilibrium condition, 4.0 mol SO{~}3~ is found to be present. What are the equilibrium concentrations of SO{~}2~ and O{~}2~?a) Both SO2and O2are 4.0 molar
b) SO2is 6.0 M and O2is 4.0 M
c) Both SO2and O2are 6.0 molar
d) SO2is 14.0 M and O210.0 M
26. For the reaction: 2NO(g) + 2H{~}2~(g) <-----> N{~}2~(g) + 2H{~}2{~}O(g) at equilibrium in a 2.0 L container at 25° C. Suppose initially 3.00 moles each of each component are put into the container. At equilibrium 2.00 mol of NO is present. What is the value for K{~}c~ for the reaction at his temperature?a) 3.4
b) 0.14
c) 0.25
d) 7.0
e) 0.0625
27. For the reaction: 2NO(g) + 2H{~}2~(g) <----->N{~}2~(g) + 2H{~}2{~}O(g) at equilibrium in a 2.0 L container at 25° C. Suppose the volume of the container is suddenly doubled to 4 L. Would the value of Q immediately after the volume change be less than or greater than K{~}c~, and in which direction would the reaction shift in order to return to equilibrium?a) Less than; right
b) Greater than; right
c) Less than; left
d) Greater than; left
e) Q = Kc; Equilibrium will not shift
For the equilibrium H{~}2~(g) + I{~}2~(g) <-----> 2HI(g) (DH{~}f~° for HI = + 25.9 kJ/mol) use the following choices for questions #28-#30 to determine in which direction will the equilibrium shift if:a) left
b) right
c) no change
28. HI(g) is removed.

29.The container volume is suddenly doubled.

30. The temperature of the system is doubled.

31. For the dimerization of NO{~}2~, 2NO{~}2~ <-----> N{~}2{~}O{~}4~. K{~}c~ = 215 at 22° C. Suppose that 0.0456 mol/L of the brown gas NO{~}2~ were detected spectroscopically in a closed container. What must be the concentration of the colorless gas N{~}2{~}O{~}4~, in the same container, assuming a state of equilibrium exists?a) 44.7 mol/L
b) 9.8 mol/L
c) 0.45 mol/L
d) 2.22 mol/L
32. For the reaction A(g) + B(g) <-----> C(g) + D(g), suppose that the concentrations of these gases were the following in an equilibrium mixture: \[A\] = 0.5, \[B\] = 4.0, \[C\] = 6.0, and \[D\] = 8.0 in a 1 L container. How many moles of D would have to be added to the mixture to raise the concentration of A to 1.0 M?a) 12.1 mol
b) 0.5 mol
c) 0.034 mol
d) 8.034 mol
33. Given the following equilibrium reaction: ZnCO{~}3~(s) <----->ZnO(s) + CO{~}2~(g). Which one of the following statements is true?a) K = [CO2][ZnO]/[ZnCO3]
b) The system cannot come to equilibrium.
c) Raising the partial pressure of CO2will cause more ZnCO3(s) to form.
d) Increasing the volume will cause more ZnCO3(s) to form.
e) None are true.

h2. KEY

1)b 2)d 3)a 4)b 5)d 6)d 7)b 8)b 9)b 10)c 11)d 12)c 13)a 14)d 15)a 16)c 17)c 18)a 19)b 20)c 21)d 22)e 23)a 24)d 25)c 26)d 27)d 28)b 29)c 30)b 31)c 32)a 33)c
1)2
2)4
3)1
4)2
5)4
6)4
7)2
8)2
9)2
10)3
11)4
12)3