Key Exam #2, version A

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1. The energy required to increase the surface area of a liquid by a unit amount is called

A) capillary action
B) surface tension
C) viscosity
D) cohesion

2. Which of the following is an example of an exothermic process?

A) melting
B) subliming
C) freezing
D) boiling

3. If 10.0 kJ of heat are added to a 15.5 g ice cube at -5.00oC, what will be the resulting state and temperature of the water? Hfusion = 6.01 kJ/mol, Hvaporization = 40.67 kJ/mol, specific heat (ice) = 2.09 J/gK, specific heat (water) = 4.18 J/gK, specific heat (steam) = 1.84 J/gK.

A) liquid, 13.9oC
B) liquid, 72.0oC
C) gas, 103oC
D) gas, 134oC

4. Which of the following will exhibit no change in temperature when 27 J of heat is removed?

A) 100 g H2O(s) at -10oC
B) 100 g H2O(g) at 110oC
C) 100 g H2O(l) at 75oC
D) 100 g H2O(l) at 0oC

5. The critical temperature and pressure of CS2 are 279oC and 78 atm, respectively. At temperatures above 279oC, CS2 can only occur as a _____.

A) solid
B) liquid
C) gas
D) supercritical fluid

6. A substance whose triple point occurs at 222K and 3.93 atm will

A) melt rather than sublime when heated at 1 atm.
B) sublime rather than melt when heated at 1 atm.
C) not exist as a gas at pressures greater than 3.93 atm.
D) not exist as a solid at pressures greater than 3.93 atm.

7. The atoms on the corner of a unit cell in an FCC arrangement are shared by how many unit cells?

A) just 1
B) 2
C) 4
D) 8

8. Lead (Pb) crystallizes in a face-centered cubic arrangement. If a unit cell of lead has an edge length of 4.95 x 10-8 cm, calculate the density of lead in g/cm3.

A) 9.85 g/cm3
B) 11.4 g/cm3
C) 13.2 g/cm3
D) 14.7 g/cm3

9. Which type of solid is soft and has a low melting point and low electrical conductivity?

A) covalent-network
B) molecular
C) metallic
D) ionic

10. Potassium hydroxide readily dissolves in water owing to

A) strong solute-solute interactions.
B) strong solvent-solvent interactions.
C) strong solute-solvent interactions.
D) weak solvent-solvent interactions.

11. Which of the following should be immiscible with carbon tetrachloride, CCl4.

A) C8H18
B) Br2
C) CH3OH
D) C3H8

12. Which of the following units of concentration is temperature dependent. Hint: for each of the different units, think about which one's have numerators or denominators whose value would depend on the temperature.

A) molarity
B) molality
C) mass percent
D) mole fraction

13. Pressure has an appreciable effect on the solubility of

A) gases in liquids.
B) liquids in liquids.
C) solid in liquids.
D) all of the above

14. What is the molality of a solution prepared by dissolving 2.21g of KBr in 897g of water?

A) 0.0167 m
B) 0.0186 m
C) 0.0207 m
D) 2.46 m

15. What is the molality of lead nitrate in 0.726 M Pb(NO3)2 aqueous solution? The density of the solution is 1.202 g/mL.

A) 0.476 m
B) 0.650 m
C) 0.755 m
D) 8.19 m

16. Calculate the mole fraction of He in a gaseous solution containing 4.0 g of He, 6.5 g of Ar and 10.0 g of Ne.

A) 0.11
B) 0.60
C) 0.86
D) 1.5

17. Which of the following will have the lowest freezing point?

A) pure water
B) 1.0 M NaCl
C) 0.5 M MgCl2
D) 0.75 M Fe(NO3)3

18. A solution containing 100 g of unknown liquid in 900 g of water has a freezing point of -3.33Co. What is the molecular weight of the unknown? Tf = Kf m where Kf for water is 1.86oC/m.

A) 62.1 g/mol
B) 69.0 g/mol
C) 161 g/mol
D) 333 g/mol

19. The vapor pressure of pure water at 25oC is 23.8 torr. Determine the vapor pressure of water at 25oC above a solution containing 35.0 g of urea (60.0 g/mol) dissolved in 75.0 g of water. PA = XAPA

A) 0.881 torr
B) 2.90 torr
C) 20.9 torr
D) 27.1 torr

20. The phenomenon used to differentiate colloids from true solutions is called

A) Osmosis
B) Henry's law
C) Tyndall effect
D) Raoult's effect

21. What are the units for the rate constant, k for a first order reaction?

A) M/s
B) 1/(Ms)
C) 1/(M2s)
D) 1/s

You will need to use the following graph and corresponding reaction to answer the remaining test questions (22-25). A scientist is studying the following reaction:

CH4(g) + 2O2(g) CO2(g) + 2H2O(g)

She begins by plotting data for the concentration of CH4(g) as a function of time as shown in the following graph.

22. Calculate the average rate of loss of CH4 from 200 s to 400 s.

A) -0.0013 M/s
B) 0.0013 M/s
C) -0.0019 M/s
D) 0.0019 M/s

23. Determine the instantaneous rate of formation of H2O at 100 s.

A) 0.0017 M/s
B) 0.0032 M/s
C) 0.0064 M/s
D) 0.65 M/s

24. Which of the following is not a valid form of the rate of reaction.

A) -[CH4]/t
B) -[O2]/2t
C) -[CO2]/t
D) [H2O]/2t

25. What is the general form of the rate law for this reaction?

A) Rate = k[CH4]m[O2]n
B) Rate = k[CH4][O2]2
C) Rate = k[CH4]m[O2]n
D) Rate = k[CH4]m[O2]n[CO2]o[H2O]p

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