C122T1S.96(3/28/96, 1st Ed.)                               GPC - Dunwoody

          (7/10/01, 5th Ed.)

Use a Scantron sheet for Multiple Choices (2pts each). Do not write on the Periodic Table. Use back of this page to show your work/answers  for the Big Write-out Questions (10 pts each).

Note: Some of superscripts, subscripts and Greek symbols may not be properly represented in this document. If desired,  refer to the hard-copy in the Library for the correct expressions. 

1.  Matter tends to adopt a gaseous state at  A(a low temperature and a low pressure), B(a low temperature and a high pressure), C(a high temperature and a low pressure), D(a high temperature and a high pressure).

2.  Which one is  a non-polar compound ?
A(HCl), B(H₂O), C(CH₃CH₂OH), D(SO₂), E(CO₂).

3. Which exhibits the lowest vapor pressure in liquid states because of its strongest intermolecular force among the five? It must be the only polar molecule among the five?
A(CO₂), B(SO₂), C(O₂), D(H₂), E(C₈H₁₈, gasoline).

4. Which hydrocarbon has the highest vapor pressure ?   It has the weakest intermolecular force (Londonforce) among the five because of its smallest size,  hence it  has the lowest boiling point.
A(CH₄, methane), B(C₂H₆, ethane), C(C₃H₈, propane), D(C₄H₁₀, butane), E(C₈H₁₈, octane,  gasoline).

5. Which of the following decreases as the strength of the intermolecular attractive forces increases?
A(The heat of vaporization of a liquid), B(The normal boiling temperature of a liquid),
C(The extent of deviations from the ideal gas law, for a gas), D(The sublimation temperature of a solid), E(The vapor pressure of a liquid).

6. What is the  the dominant form of the intermolecular forces among HCl molecules?
(A)Gravitational, (B)Coulomb, (C)Dipole-Dipole, (D)London, (E) H-Bonding Force.

7. What is the dominant force that holds octane molecules in the liquid gasoline together?
(A) Newton's Gravitational Force, (B)Coulomb's Electrostatic Force, (C) Keesom's Dipole-Dipole Force, (D)London's Dispersion (Induced-Dipole/Induced-Dipole) Force, (E) H-Bonding Force.

8. The molecules in a sample of SO₂ are attracted to each other by a combination of
A(H-Bonding and London forces), B(H-bonding and ionic bonding), C(Dipole-dipole interactions and covalent bonding), D(Dipole-dipole interactions and London forces), E(London forces and ionic bonding), the first force being dominant over the second one.

9. Given boiling points (BP) for Ne(-256^oC), N₂(-61^oC), H₂O(100^oC), Hg(883^oC); a BP of CHCl₃(Chloroform) must be A(-260^oC), B(-87^oC), C(62^oC), D(108^oC), E(5660^oC).

10. Which has the highest surface tension?
A(Cold Water,  5^oC), B(Warm Water,  45^oC), C(Cold Vodka, 40% C₂H₅OH,  5^oC), D(Warm Vodka, 40% C₂H₅OH,  45^oC).

11. SI unit of vapor pressure is  A(kg m/s²), B(kg m²/s²), C(kg/(m²s²)), D(kg/(m²s)), E(kg/(ms²)).

12. Ammonia(NH₃ ), instead of freon(CCl₂F₂),  was used in old refrigerators.  The heat of vaporization of ammonia is 23.4kJ/mol. If 1.00kg of NH₃ is vaporized, (1) how many kJ of heat will be absorbed? (2) how many  kg of water can be frozen from this in a refrigerator ? Heat of fusion of water is 6.01kJ/mol.
A(171kg;  0.51kg), B(343kJ; 1.03kg), C(685kJ; 2.06kg),  D(1,370 kJ; 4.12 kg), E(2,740kg; 8.24 kg)

13. H₂O has a triple point of (0.01^oC, 0.00603 atm) and a critical point of (374 ^oC, 218 atm).
What phase changes will be observed if it is being heated from -100 oC to +400 oC at 0.0001 atm?
A(Solid ->  Gas), B(Liquid -> Gas), C(Solid -> Liquid -> Gas), D(Solid -> Liquid -> Supercritical Fluid).

14. Detergents (a) increase, (b) decrease, surface tension and viscosity of water by (c) weakening, (d) reinforcing, interactions (i.e., "Hydrogen Bonding") among water molecules.
A(a,c), B(a,d), C(b,c), D(b,d), E(-).

15. Which of the statements regarding solids A through D is false?
A(Diamond is a covalent crystal), B(The size of the unit cell of Li and Cs is same),
C(Molecular crystals usually have low melting points), D(Metallic crystals are usually good electrical conductors),
E(All of the statements A through D are correct).

16. Which is a correct order of  increasing boiling points among hydrogen halides ( or decreasing vapor pressure among HX)?
A( HF<HCl< HBr<HI ),  B( HI<HBr< HCl<HF) , C( HCl<HBr< HI<HF), D( HF<HI< HBr<HCl ).

17. Because of its weakest intermolecular force, this has the lowest boiling point.
A(CF₄), B(HF), C(Cu), D(KI), E(SiF₄)

18.  What type of solid should CCl₄ form?  A(Molecular), B(Ionic), C(Covalent network), D(Metallic).

19.   Molecular solids have much (a) lower, (b) higher, melting point, and are softer than ionic, metallic, and ovalent network solids because of their (c) weaker, (d) stronger intermolecular forces than the rest.
A(a,c), B(a,d), C(b,c), D(b,d).

20. This ionic compound is used as a fire-brick in a blast furnace since it has the highest melting point because of its larghest lattice energy
      among the five. A(NaCl),  B( Na₂O), C(CaO), D( MgBr₂), E(MgO).

21. Which unit cell has incorrect values of # of atoms /cell, a coordination number and a packing efficiency?
      A(Simple cubic; 1, 6, 52%), B(Body-centered cubic; 2, 8, 68%), C(Face-centered cubic; 4, 12, 74%),
      D(Hexagonal; 4, 12, 74 %), E(None of these).

22.  In the structure of NaCl ionic crystals, chloride ions form (a) body-centered cubic lattice, (b) face- centered cubic lattice, and soduim ions fill in all of the empty (c) tetrahedral holes, (d) octahedral holes formed in the cubic lattice of Cl^-.
A(a,c), B(a,d), C(b,c), D(b,d), E(-).

23. A Zn²⁺ in zinc blende(ZnS) has (a) 4, (b) 6 nearest S^2- ions, each Zn²⁺ occupies four of eight (c) tetrahedral, (d) octahedral holes in the face-centered cubic lattice of S^2-.
     A(a,c) ,B(a,d), C(b,c), D(b,d).

24. The unit cell in a certain lattice consists of a cube formed by an anion at each corner, an anion in the center, and a cation at the center of each face,  the unit cell contains a net
A( 2 anions and 2 cations),  B( 2 anions and 3 cations),  C( 3 anions and 2 cations),
D( 3 anions and 4 cations),  E( 4 anions and 3 cations).

25. Which of the following statements is/are false?
a. The hexagonal closest-packed structure has ABAB---  type of a stacking pattern.
b. A body-centered cubic unit cell has four atoms per unit cell.
c. For unit cells having the same edge length, a simple cubic structure would have a smaller density then a body-centered cube.
d. atoms in a solid consisting of only one element would have six nearest neighbors if the crystal structure was a simple cubic array or lattice.
A(a), B(b), C(b, c), D(a, d), E(b, c, d).

26. Which of the following statements about phase transitions are true?
a. No temperature change is observed during a phase change.
b. Vaporization is an exothermic process.
c. When a phase change occurs, no energy is transferred to or from the substance.
d. When cooling of a given amount of a substance, the rate at which cooling occurs is a function of the mass of the substance and its specific heat.
e. The heat of fusion of ice would determine how much energy would be required to change the temperature of a 10g block of ice from -20^oC to -2^oC.
A(a and c),  B(a and d),  C(b and c),  D(b, c and d),  E(d only).

27. White phosphorus, P₄,  is a white, waxy solid melting at 44 ^oC to a colorless liquid. The liquid has a vapor pressure of 400.0 mmHg at 252.0^oC  and 760.0 mmHg at 280.0^oC . What is the heat of vaporization of this substance?
A(23.3 kJ/mol), B(6.44 kJ/mol), C(433 kJ/mol), D(53.3 kJ/mol), E(46.6 kJ/mol).

29. Which of the following concentration measures will change in its value as the temperature of a solution changes?
A(Mass % or Mass fraction), B(Mole % or Mole fraction), C(Molality), D(Molarity), E(All of  these).

30. Rank the following compounds according to increasing solubility in H₂O.
a. CH₃-CH₂-CH₂-CH₃ ,   b. CH₃-CH₂-O-CH₂-CH₃ ,    c. CH₃-CH₂-OH ,  d. CH₃-OH .
A (a<c<d<b),  B (a<b<c<d), C (c<d<b<a), D (a<b<c<d), E(None of above is correct).

31. When a substance dissolves in water, heat energy is released if
A(the lattice energy is positive), B(the hydration energy is positive),
C(the hydration energy is greater than the lattice energy),
D(the lattice energy is greater than the hydration energy),
E(the hydration energy is negative).

32. A correct statement of Henry's Law is
A (The concentration of a gas in a solution is directly proportional to temperature),
B (The concentration of a gas in a solution is inversely proportional to temperature),
C (The concentration of a gas in a solution is directly proportional to pressure),
D (The concentration of a gas in a solution is inversely proportional to pressure),
E (The concentration of a gas in a solution is independent of temperature).

33. Which of the following would decreases when a nonvolatile solute is added to a volatile solvent?
A(the vapor pressure), B(the boiling point), C(the freezing point), D(the osmotic pressure), E(A & C).

34. (a)Mg(OH)₂, (b)Ca(OH)₂, (c)Sr(OH)₂, (d)Ba(OH)₂ exhibits the highest solubility in H₂O because it has the (e) largest, (f) smallest lattice energy among the four.
A(a,e), B(a,f), C(d,e), D(d,f), E(none of these).

35. Mg ²⁺ has (a) smaller , (b) larger , hydration energy than Ba²⁺.  This is because Mg ²⁺ is (c) smaller , (d) larger, than Ba²⁺.
A(a,c), B(a,d), C(b,c), D(b,d), E(none of these).

36. (a)MgSO₄, (b)CaSO₄, (c)SrSO₄, (d)BaSO₄ ,exhibits the highest solubility in H₂O because it has the (e) largest, (f) smallest, hydration energy among the four while the lattice energies of the four compounds do not differ too much.
A(a,e), B(a,f), C(d,e), D(d,f), E(none of these).

37. Gas in general are most soluble in water or any other solvent at
A(low pressure and low temperature), B(low pressure and high temperature),C(high pressure and low temperature), D(high pressure and high temperature),

38.  The formula of a common soap, sodium stearate, is  a(C₇H₁₅COONa), b(C₁₇H₃₅COONa).
 In a cleaning action, the (c) hydrophobic tail, (d) hydrophilic head of soap molecules binds to oily dirts to take it off from fabrics.   A(a,c), B(a,d), C(b,c), D(b,d).

39. What force plays a major role in the cleansing action of a soap when it binds to oily dirts.?
A(Gravitational Force), B(Coulomb Force), C(London Force), D(Nuclear Force).

40. Find  a  molarity of sulfuric acid (H₂SO₄ , 38 % by mass) in an  auto battery solution. Density of the solution is 1.285g/cm³.  A(1.0), B(2.0), C(3.0), D(4.0), E(5.0) M.

41. The solubility of CO₂ is 0.161g in 100 mL of water at 20^oC and 1 atm of pressure of CO₂.
Which is larger (A) A mass of CO₂ is dissolved in a can (355mL) of a soft drink when it is carbonated under a pressure of 5.0 atm of CO₂, or (B) A mass of a  recent penny (=2.5g) ?

42. Find molarity of CO₂ in the soft drink above.
A(0.1),  B(0.2), C(0.4), D(0.8), E(1.0) M.

43. Vapor pressure of water at 25^oC is 23.8mmHg.  225 g of glucose (C₆H₁₂O₆) is dissolved in 1.000 kg of water.
(1) Find mole fraction of glucose, then (2) predict a new vapor pressure of the IV injection solution.
A(0.011; 21.3mmHg),  B(0.011; 23.3mmHg),  C(0.022; 21.3 mmHg), D(0.022; 23.3 mmHg).

44. Estimate a molarity of the solution above assuming that the molarity has the same value as the molality. Then precdict a osmotic pressure developed at 25^oC when the solution is separated from a pure water  with a semipeameable membrane.
A(0.1 atm),  B(0.2 atm),  C(0.3 atm), D(0.4atm). E(0.5 atm).

45.  333 grams of  ethylene glycol(CH₂OHCH₂OH) is added to 1.000 L of  water(d=0.997g/mL). Find the freezing point.       K_f(H₂O)=1.858^oC/m
A(-5.0^oC), B(-10.0^oC), C(-20.0^oC) D(-30.0^oC), E(-40.0^oC).

46. Which of the following will have the lowest freezing point?
A(a 0.1 m aqueous solution of NaCl), B(a 0.1 m aqueous solution of sucrose), C(a 0.1 m aqueous solution of K₂SO₄), D(a 0.1 m aqueous solution of CoCl₃), E(a 0.1 m aqueous solution of (NH₄)₂CO₃).

47.  Temperature of a water in a pressure cooker reached 105^oC, the pressure inside must be
        about  A(1.1), B(1.2), C(1.5), D(2.0), E(5.0) atm.  ( DeltaH_vap(H₂O)=40.7kJ/mol). Show your work.

48. From the average atmospheric pressure, 650 mmHg,  of Denver (CO), predict boiling point of water in the area using Clausius-Clapeyron Equation. Heat of vaporization of water is 40.7 kJ/mol. Show your work.
A(92), B(95), C(97), D(99), E(100) ^oC.

   -   Answer any one of the following questions.  These questions are 5 points each.  You must show all of your work for credits.   -

I.   Explain four types of intermolecular forces between neutral molecules, so-called van der Waals force, and give examples for each:
(1) Dipole/Dipole Force, (2) Dipole/Induced-Dipole Force, (3) Induced-Dipole/Induced-diploe (London) Force, (4) Hydrogen-Bonding Force.

II. Lithium metal has a body-centered cubic lattice with all atoms at the lattice points and a unit cell length of 3.509 (350.9 pm). The density(Li) is 0.534 g/cm³.
(1) Find the mass of a Li atom(g). (2) Calculate Avogadro's number(N_A).

III. The vapor pressure of benzene is 100mmHg at 26.1^oC and 400mmHg at 60.0^oC. Find the heat(enthalpy) of vaporization (Delta H_vap) of benzene in (1) Joule, and (2) cal. (3) What is the boiling point of benzene at 1 atmospheric pressure? (4) Explain why Delta H_vap of benzene is smaller than that of water in terms of intermolecular forces.

IV. An antiseptic solution contains hydrogen peroxide, H₂O₂, in water. The solution is 0.655m in H₂O₂. Find the concentration in terms of (1) mole fraction of H₂O₂, (      ); (2) Molarity, (      )M; (3) percentage(w/w), (      )%; (4) parts per million(w/w), (      )ppm.

V. (1) How many gal of ethylene glycol(CH₂OHCH₂OH, d=1.141g/mL) must be added to 4.00 gal of  water(d=0.997g/mL) for an engine-cooling to have  a freezing point of -20.0^oC(=-4.0^oF)? Kf(H₂O)=1.858^oC/m, (2) What is the boiling point of the mixture ? Kb(H₂O)=0.512^oC/m.

VI.  Show that the gravitational force is insignificant compared to the Coulomb force in holding ions in a NaCl crystal together. (The interionic distance between Na⁺ and Cl^- ;  r=282pm)

KEY  to the Multiple Choice Question

(2/4/05, 9/12/01, 9/15/99, 3/28/96, rev., MHK)