- Arrange the following substances in the expected order of increasing boiling pt and give the types of intermolecular forces in each. H2O, NH3, CH4, CH3CH3. (5pts)
- Using figure 10.10 from your book, calculate the entropy change of vaporization of water. (15pts)
- At 25 °C and 2.00 atm, the solubility of CO2(g) in water is 0.0678 M. When air at 1 atm and 25 °C is in equilibrium with water, Use Henry’s law to get the concentration of dissolved CO2? The partial pressure of CO2 in air is approximately 4.0 x 10-4 atm. (10pts)
- The vapor pressure of benzene (C6H6) at 25°C is 95.1 mm Hg. What is the vapor pressure of benzene above a solution in which 5.05 g of benzoic acid, C6H5COOH, is dissolved in 245 g C6H6? Use Raoult’s law. (10pts)
- Draw a picture showing hydrogen bonding between several molecules of water (2D is ok here) (2pts)
- What is the normal boiling pt in °C of ethanol if a solution prepared by dissolving 13.0 g NaCl in 285 g of ethyl alcohol has a boiling pt of 79.1 °C? Assume complete dissociation of NaCl. The Kb for ethanol is 1.22 (°C kg)/mol. (10pts)
- The experimental dipole moment of BrCl is 0.518 D and the distance between atoms is 213.9 pm. What is the percent ionic character of the BrCl bond? (μ = Q x r) 1D = 3.336 x 10-30 Cm (5pts)
- Ethyl alcohol, CH3CH2OH is miscible with water but 1-heptanol CH3CH2CH2CH2CH2CH2CH2OH is only slightly miscible in water. Explain. (3pts)
- Give the name of the packing, the name of the unit cell, and the number of atoms in the unit cell for each of the following packing structures/unit cell diagrams. (9 pts)
(a)
(b)
(c)
- Oxygen has a triple point at 54.3 K and 1.14 mm Hg and a critical point at 154.6 K and 49.77 atm. The density of the liquid is 1.14 g/cm3 and the density of the solid is 1.33 g/cm3. Sketch a phase diagram labeling all points of interest (not to scale). (10pts)
Pressure (atm)
Temperature (K)
- At 500 K, the vapor pressure of Hg is 39.3 mm Hg. Use the Clausius-Clapeyron equation to find the temperature at which the vapor pressure of mercury is 114.4 mm Hg. ΔHvap = 59.229 kJ/mol for Hg (10pts)
- Express the following aqueous concentrations in the unit indicated: (6pts)
- 0.0025 g KI/L water as ppm of KI
- 0.0035% NaCl by mass as ppb NaCl
- 2.40 ppm F–, as molarity of fluoride ion.
- How many mL of ethanol, CH3CH2OH (d = 0.789 g/mL), must be mixed with 125 mL of benzene, C6H6 (d = 0.879 g/mL) in order to produce a solution that is 0.0654 m ethanol? (15 pts)