answer all the questions with a b c or d to test your peformance 1. Formation of a solution can often be visualized as a three-step process.

Step 1. Solvent molecules are separated from each other to make space for the solute.

Step 2. Solute molecules are separated so they fit into spaces in the solvent

Step 3. Separated solute and solvent are brought together filling in the spaces.

All of the fundamental principles below are important in understanding the formation of solutions except which one?

A. Starting at equilibrium, moving particles apart while in the solid or equilibrium phases requires added energy proportional to the attractive forces.
B. Bringing particles together releases energy in proportion to their attractive forces.
C. The total of the energies in steps 1 to 3 indicates if a solution will form.
D. Molecules with similar molecular masses are required to form solutions.
2. Bromine has a normal boiling point of 59 °C, and iodine boils at 184 °C. The I2 molecule is much larger than Br2 (atomic radii are 114 and 133 pm, respectively). Which is the best reason for the large difference in boiling points?

A. Bromine is a liquid and boils; iodine is a solid and sublimes.
B. The intramolecular bonds in I2 are much weaker than those in Br2.
C. The I2 electron clouds are much more polarizable than the Br2 electron clouds, resulting in much stronger London forces.
D. The mass of iodine is much greater than the mass of bromine.
3.

Ethanoic acid (HC2H3O2 or CH3CO2H or CH3COOH) has a much lower vapor pressure than ethanol (CH3CH2OH). What is the most reasonable explanation?

A. The polarizability of two oxygen atoms increases the London forces of attraction in ethanoic acid compared with ethanol.
B. Hydrogen bonding in ethanoic acid is the strongest attractive force and is mainly responsible for the observed data.
C. Ethanol has an –OH group and can hydrogen bond; therefore, the London forces must cause the effect.
D. Both ethanol and ethanoic acid have an –OH, so the difference is the dipole of the second oxygen that increases the attractive forces.
Questions 4-8 refer to the following information.

The synthesis of solid lead(II) sulfide can be expressed in the equation

Which statement about this reaction as temperature is increased is most reasonable?

A. This reaction will become thermodynamically favored because the entropy change is expected to be positive.
B. This reaction will always be thermodynamically favored because the entropy change is expected to be positive.
C. This reaction will always be thermodynamically unfavored because the entropy change is expected to be positive.
D. This reaction will become thermodynamically unfavored because the entropy change is expected to be negative.
5. Which of the reactions above represent the formation of the crystal lattice?

A. ΔH° = ΔH°(5)
B. ΔH° = 2ΔH°(3) + ΔH°(4)
C. ΔH° = ΔH°(3)/2 + ΔH°(4)
D. ΔH° = ΔH°(3) + 2ΔH°(4)
6. If 5.0 g of lead and 1.0 g of sulfur are reacted according to the equation above, what will be left in measurable amounts (more than 1 mg) in the reaction vessel?

A. Lead and lead sulfide only
B. Lead sulfide only
C. Lead sulfide and sulfur only
D. Lead sulfide, lead, and sulfur
7. Which of the following enthalpies will have a negative sign?

A. ΔH(1) and ΔH(2) only
B. ΔH(4) and ΔH(5) only
C. ΔH(2) and ΔH(4) only
D. ΔH(1), ΔH(2), and ΔH(3) only
8. Which of the following, without regard to sign, will have the same numerical value as the lattice energy, also without regard to sign?

A. ΔH°(5)
B. ΔH°(4)
C. ΔH°(3)
D. ΔH°(1) + ΔH°(2)

Questions 9-12 refer to the following information.

Questions refer to the cell diagrams and their corresponding E°cell values for the three galvanic cells listed in the table below.

Galvanic Cell Cell Diagram E°cell
1 Zn | Zn2+(1.0 M) || Pb2+(1.0 M) | Pb 0.63
2 Mg | Mg2+(1.0 M) || Pb2+(1.0 M) | Pb 2.24
3 Mg | Mg2+(1.0 M) || Zn2+(1.0 M) | Zn ?
The chemical reaction occurring in the first galvanic cell is

Zn + Pb2+ → Zn2+ + Pb

What is the standard cell potential for galvanic cell 3 depicted in the table above?

A. 1.61 V
B. 2.77 V
C. -1.61 V
D. 0.18 V
10. What is the chemical reaction under study in galvanic cell 3?

A. Pb2+ + Mg2+ → b2+ + Mg
B. Zn + Pb2+ → Zn2+ + Pb
C. Mg + Zn2+ → Mg2+ + Zn
D. Zn + Mg2+ → Zn2+ + Mg
11. If the concentration of Mg2+ is changed from 1.0 M to 0.1 M in the galvanic cells above, what will happen to the observed cell voltages in galvanic cells 2 and 3?

A. The voltage in both galvanic cells 2 and 3 will increase.
B. The voltage will decrease in both galvanic cells 2 and 3.
C. The voltage in galvanic cell 2 will increase and will decrease in galvanic cell 3.
D. The voltage in galvanic cell 3 will increase and will decrease in galvanic cell 2.
12. Rank Mg, Pb, and Zn from the metal that is easiest to oxidize to the metal that is the most difficult to oxidize.

A. Mg > Pb > Zn
B. Zn > Pb > Mg
C. Mg > Zn > Pb
D. Pb > Zn > Mg