Chem 1C – Chapter 16 – CLAS

e-mail ⇒ benzene4president@gmail.comwebsite ⇒ clas.sa.ucsb.edu/staff/terri/drop-in ⇒ M/W 3-4, T 2-3, and F 1-31. Indicate the types of forces present for each of the following substances:

a. CCl4 f. Arb. HF g. H2Sc. NH4Br h. KOH d. F2 i. BH3

e. CH3OH j. H2CO

2. Using intermolecular forces predict the following:a. highest melting point F2 or Br2

b. highest melting point HF or HClc. highest boiling point HOCH2CH2OH or CH3CH2OHd. highest boiling point CH3CH3 or CH3CH2CH3

e. highest vapor pressure CH3CH2OH or CH3OCH3

f. highest vapor pressure CCl4 or CH2Cl2

g. highest freezing point MgO or H2Oh. highest surface tension C14H30 or C24H50

3. Consider the following phase diagrams for water and carbon dioxide respectively – which phase is the most dense for each substance? How does pressure affect the MP and BP for each substance?

4. Pure compound Z has a triple point at 18 ° C and 72 torr, a normal melting point at 21 °C, and a normal boiling point at 87 °C. Which of the following statements regarding compound Z is/are correct?a. The density of the solid is greater than that of the liquid.b. Sublimation occurs if starting with a solid at a constant temperature of 17 °C the pressure is decreased until a

phase change occurs. c. Condensation occurs if the temperature is decreased from 55 °C to 13 °C at a constant pressure of 1.00 atm.

5. The enthalpy of vaporization for water is 44 kJ/mol. What is the boiling point if the atmospheric pressure were 0.33 atm?

ln (P2P1 ) = - ΔH vap

R (1T 2– 1

T 1 )6. How much heat is required to take 10 g of ice from -31 °C to vapor at 155 °C if the pressure is hel constant at 1 atm?

(Csolid = 2.03 J/g°C , Cliquid = 4.18 J/g°C , Cgas = 2.02 J/g°C, ΔHfus = 6.01 kJ/mol, and ΔHvap = 40.7 kJ/mol)

7. Determine the final temperature if a 25 g cube of ice at -7 °C is placed in 180 g of water at 64 °C and allowed to

come to equilibrium. (Csolid = 2.03 J/g°C , Cliquid = 4.18 J/g°C , Cgas = 2.02 J/g°C, ΔHfus = 6.01 kJ/mol, and ΔHvap = 40.7 kJ/mol)

8. Copper has an inter-planar spacing of 1.36 Å. Calculate the wavelength of the X ray that should be used if θ is 15° (assume n=1).

9. Zinc crystallizes in a cubic closest packed structure. The radius of a zinc atom is 135 pm. Calculate the density in g/mL for solid zinc.

10. Titanium metal has a body-centered cubic unit cell. The density is 4.50 g/cm3. Calculate the atomic radius in angstroms of titanium. (1010Å= 1m)

11. The unit cell in this two-dimensional crystal contains __________ Xs and __________ Os.a. 1, 1 X X X X Xb. 2, 1 O O O O c. 1, 2 X X X X X d. 4, 1 O O O Oe. 1, 4 X X X X X

12. Assume the two-dimensional structure of an ionic compound MxAy is

What is the empirical formula of this ionic compound?

13. Consider the following cubic closest packed structures. For each compound determine where the ions are in the lattice.a. NaCl (Na+ = 95 pm, Cl– = 181 pm )b. ZnS (Zn2+= 74 pm, S2– = 184 pm)c. CaCl2 (Ca2+ = 99 pm, Cl– = 181 pm)

14. Identify the type of doping in each of the following.a. Gallium doped with tinb. Antimony doped with germaniumc. A material is made from Al, Ga, and As. The mole fractions of these elements are 0.15, 0.26, and 0.59,

respectively.

10. (5 points) In general, how can one increase the conductivity in pure semiconductors? a. Increase the temperature b. Decrease the temperature c. Dope the semiconductor to produce a p-type semiconductor d. Both A and C are correct e. Both B and C are correct