1. The vapor pressure of an unknown liquid was measured as described in this experiment: Pressure Measurements Temp. °C VP Temp. (in Kelvin) (mm Hg) In VP 1/T (mm Hg) Observed Air Pressure 5.5 773.1 731.3 41.8 21.3 837.0 736.7 41.0 983.3 750.5 a. Fill in the rest of the table above. The observed vapor pressure is actually the sum of the vapor pressure of the unknown liquid and the pressure of air in the flask. In order to determine the vapor pressure of liquid you need to subtract the air pressure from the observed pressure. Note that the pressure of air in the flask changes with temperature. Show your calculations in the space below.

The pressure above a pure sample of solid Substance X at -64. °C is lowered. At what pressure will the sample sublime? Use the phase diagram of X below to find your answer. pressure (atm) solid atm 200 liquid 400 X gas temperature (K) Note: your answer must be within 0.25 atm of the exact answer to be graded correct. 600

3. Using your knowledge of IMF's, rank the following in order of increasing expected vapor pressure. Make sure to explain your logic and indicate which intermolecular force(s) each is capable of forming. H H H H H H H H H ✓ с H H H C H H C. H

Study the following phase diagram of Substance X. 24 solid liquid gas 100 200 300 temperature (K) Use this diagram to answer the following questions. Suppose a small sample of pure X is held at -221. °C and 15.6 atm. (choose one) v What will the state of the sample? Suppose the temperature is held constant at -221. °C but the (choose one pressure is decreased by 7 atm. What will happen to the sample? (choose one) Nothing. It will melt. It will freeze. It will boil. It will condense. It will sublime. It will deposit. Suppose, on the other hand, the pressure is held constant at 15.6 atm but the temperature is increased by 160. °C. What will happen to the sample? pressure (atm)