Calculate the solubility of argon in water at an atmospheric pressure of 0.360 atm (a typical value at high altitude).  Atmospheric Gas Mole Fraction kH mol/(L*atm) N2 7.81 x 10-1 6.70 x 10-4 O2 2.10 x 10-1 1.30 x 10-3 Ar 9.34 x 10-3 1.40 x 10-3 CO2 3.33 x 10-4 3.50 x 10-2 CH4 2.00 x 10-6 1.40 x 10-3 H2 5.00 x 10-7 7.80 x 10-4      M

Fluoridation of city water supplies has been practiced in the United States for several decades. It is done by continuously adding sodium fluoride to water as it comes from a reservoir. Assume you live in a medium-sized city of 150,000 people and that 660 L (170 gal) of water is used per person per day. What mass of sodium fluoride (in kilograms) must be added to the water supply each year (365 days) to have the required fluoride concentration of 1 ppm (part per million)that is, 1 kilogram of fluoride per 1 million kilograms of water? (Sodium fluoride is 45.0% fluoride, and water has a density of 1.00 g/cm3.)

The dispersed phase of a certain colloidal dispersion consists of spheres of diameter 1.0 102 nm. (a) What are the volume (V=43r2) and surface area (A = r2) of each sphere? (b) How many spheres are required to give a total volume of 1.0 cm3? What is the total surface area of these spheres in square meters?

Some lithium chloride, LiCl, is dissolved in 100 mL of water in one beaker, and some Li2SO4 is dissolved in 100 mL of water in another beaker. Both are at 10 C, and both are saturated solutions; some solid remains undissolved in each beaker. Describe what you would observe as the temperature is raised. The following data are available to you from a handbook of chemistry:

6-21 Are mixtures of gases true solutions or heterogeneous mixtures? Explain.

6-28 Which pairs of liquids are likely to be miscible? (a) H2O and CH3OH (b) H2O and C6H6 (c)C6H14 and CCI4 (d) CCI4 and CH3OH

6-103 A swimming pool containing 20,000. L of water is chlorinated to have a final CI2 concentration of 0.00500 M. What is the CI2 concentration in ppm? How many kilograms of CI2 were added to the swimming pool to reach this concentration?

In the 1986 Lake Nyos disaster (see the chapter introduction), an estimated 90 billion kilograms of CO2 was dissolved in the lake at the time. (a) What volume of gas is this at standard temperature and pressure? (b) Assuming that this dissolved gas was in equilibrium with the normal partial pressure of CO2 in the atmosphere (0.038%, or 0.29 torr), use the Henrys law constant for CO2 in water to estimate the volume of Lake Nyos.

Starch contains CC, CH, CO, and OH bonds. Hydrocarbons have only CC and CH bonds. Both starch and hydrocarbons can form colloidal dispersions in water. Which dispersion is classified as hydrophobic? Which is hydrophilic? Explain briefly.

Heat is released when some solutions form; heat is absorbed when other solutions form. Provide a molecular explanation for the difference between these two types of spontaneous processes.