1.  Draw lewis structures for the following molecules. Give the shape of the molecule, hybridization of the central atom, polarity, and the bond angle(s).

  1. CH2F2
  1. OF2
  1. PO33-
  1. BCl3
  1. BeF2
  1. PBr5

2.  Given the following electronegativities, which covalent bond is the most polar?

Element / H / C / N / O
Electronegativity / 2.1 / 2.5 / 3.0 / 3.5

a.  C-H

b.  N-H

c.  O-H

d.  O-C

e.  O-N

3.  Which drawing represents a bonding molecular orbital for a homonuclear diatomic molecule?

4.  In ethylene (H2C=CH2), the C=C double bond results from _____ overlap of _____ orbitals and ______overlap of ______orbitals on the C atoms.

  1. σ, sp, π, p
  2. σ, sp2, π, sp2
  3. σ, sp3, π, s
  4. σ, sp2, π, p
  5. π, sp2, σ, p

5.  Nickel crystallizes in a face-centered cubic lattice. If the density of the metal is 8.908 g/cm3, what is the unit cell edge length in cm?

6.  Which of the following statements about the allotropes of carbon is false?

  1. In diamond, the carbon atoms are bonded together in a three-dimensional tetrahedral lattice.
  2. Graphite has similar properties to diamond because they are both made of only carbon atoms.
  3. Diamond is very hard and inert because of strong covalent bonds holding all the atoms together.
  4. In graphite, carbon atoms are bonded together in two-dimensional planes.
  5. Graphite is soft because only weak forces hold the planes of C atoms together.

7.  Which of the following would be a p-type doping for As?

  1. S
  2. Al
  3. Ga
  4. (b) and (c)
  5. (a) and (b)

8.  The atmosphere around the earth is warmed because _____

  1. Warm air cannot escape, as in a greenhouse
  2. Molecules in the atmosphere are warmed by radiation from the earth that retain heat
  3. Fossil fuels release heat
  4. Plants absorb CO2
  5. Plants release CO2

9.  For the following molecules, determine what Intermolecular forces are present and rank them in order of increasing strength

  1. CH4
  2. CH3OH
  3. C6H14
  4. H2O
  5. CH3NH2
  6. BBr2Cl

10.  Regarding number 9, which compound would have

  1. The highest boiling point
  2. The lowest vapor pressure
  3. The lowest melting point

11.  Which of the following polymers is an example of a block copolymer

  1. ABABBBABBABBAB
  2. ABABABABABABA
  3. AAABBBAAABBB
  4. BABABABABABABA
  5. None of the above

12.  Using the thermodynamic data, determine if the following reaction is spontaneous at only high or only low temperatures? (ΔS NO=210.7J/mol*K, N2=191.5 J/mol*K, O2=205.0 J/mol*K)

N2(g)+O2(g)+ 180.5 kJ è 2NO(g)

13.  A 0.500 g sample of naphthalene (C10H8) is burned in a bomb calorimeter containing 650 grams of water at an initial temperature of 20.00ºC. After the reaction, the final temperature of the water is 26.4ºC. The heat capacity of the calorimeter is 420 J/ºC. Using these data, calculate the heat of combustion of naphthalene in kJ/mol.

14.  Determine the final temperature when 10.0 g of aluminum at 130.0 °C mixes with 200.0 grams of water at 25.0 °C. The specific heat of aluminum is 0.901 J/g °C. (Coffee cup calorimeter problem.)

15.  Find the ΔH°rxn for C2H6(g) + 7/2 O2(g) à 2 CO2(g) + 3 H2O(g)

ΔH°f C2H6(g) = -84.7 kJ/mol

ΔH°f CO2(g) = -393.5 kJ/mol

ΔH°f H2O(g) = -241.8 kJ/mol

16.  Without doing a calculation, predict whether the entropy change will be positive or negative when each of the following reactions occurs in the direction it is written

a. 

b. 

17.  Which of the following statements about energy is true?

a.  The change in energy of the system + the change in energy of the surroundings for an exothermic reaction is negative

b.  A substance that goes from a solid to a gas has a positive work term.

c.  The enthalpy for a reaction in a bomb calorimeter is equal to the change in heat (q).

d.  The most efficient electricity conversion is electricalàthermal.

18.  The total number of σ bonds in the H-CΞC-CΞC-CΞC-CΞN molecule is

  1. 4
  2. 6
  3. 8
  4. 12
  5. 15

19.  Which of the following molecular species is stabilized by resonance?

  1. CO2
  2. N3-
  3. BH3
  4. O22-
  5. HCN

20.  If 3.4 kJ of heat flows out of the system while 4.8 kJ of work is done by the system on the surroundings, what is the internal energy?

21.  Given the following reactions,

2 S(s) + 3 O2 (g) à 2 SO3(g) ΔH = -790 kJ

S(s) + O2(g) à SO2 (g) ΔH = -297 kJ

What is ΔH° for the reaction 2 SO2(g) + O2(g) à 2 SO3(g)?

22.  Silane, SiH4, burns according to the reaction, SiH4 + 2 O2 à SiO2 + 2 H2O, with ΔH° = -1429 kJ. How much energy is released if 15.7 g of silane is burned?

23.  How much heat must be removed to change 75.0 grams of water at 25.0 °C to ice at -35.0 °C? ΔH°fusion ice = 333.55 J/g; specific heat of ice = 2.03 J/g °C

24.  The normal melting point of benzene, C6H6, is 5.5°C. For the process of melting, what is the sign of each of the following?

  1. ΔH°
  2. ΔS°
  3. ΔG° at 5.5°C
  4. ΔG° at 0.0°C
  5. ΔG° at 25.0°C

25.  Determine whether each of the following statements is true or false. If false, modify the statement to make it true.

  1. An exothermic reaction is always spontaneous.
  2. When ΔG° is positive, the reaction cannot occur under any conditions.
  3. ΔS° is positive of a reaction in which there is an increase in the number of moles.
  4. If ΔH° and ΔS° are both negative, ΔG° will always be negative.