Chemistry HW 6: Boiling Points, Evaporation, Pressure, Osmosis, and Freezing Point - Prof., Assignments of Physical Chemistry

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Homework #6 Due: October 31 Name _________________________ Chemistry 331

1. Calculate the boiling point of water of on the top of Mt. Kilimanjaro (elevation 6000 m).
2. A. How many kilograms of water can be evaporated from a 1 m2 surface in a lake on a hot summer day, if it is assumed that the limiting factor is solar insolation (1000 W/m^2 ). Assume that the length of the day is 8 hours and that the air and water temperature at both 40 o^ C. B. What volume of air is needed to hold this much water vapor at 40 o^ C. C. When the sun sets, the air temperature drops to 20 o^ C. Assuming tha the excess water vapor is precipitated as rain, calculate the weight of the rain and the amount of heat released when the water condenses.
3. One of the important factors responsible for geologic evolution (i.e. erosion) is the pressure developed by freezing of water trapped in enclosed spaces in rock formations. Estimate the maximum pressure that can be developed by water freezing to ice on a cold night (T = -10 o^ C). The densities of ice and water at – o (^) C may be taken as 0.9 g/cm (^3) and 1.0 g/cm (^3) , respectively.
4. The molar mass of a protein is determined from a measurement of the osmotic pressure. If 0.01 grams of the protein is dissolved in 1 ml. and osmotic pressure of 5 x 10-6^ atm develops at a temperature of 310 K, what is the molar mass of the protein?
5. Trehalose acts as a cryoprotectant in fungal cells. Assuming that the major effect of trehalose is to act as a solute to the lower freezing point (freezing point depression), calculate the mole fraction of trehalose that would be needed to lower than the freezing point in cell to 260 K. The enthalpy of fusion of water is ∆Hfus = 6 kJ/mol.