28 Solubility Product Problems

# 28 Solubility Product Problems - =cRTi R = 0.082 L atm...

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1 1 Sample Osmosis Problem = c R T i R = 0.082 L atm mol -1 K -1 What is the osmotic pressure produced by sea water at 300 K? Assume sea water (1.03 g/mL) has a NaCl (58 g/mol) concentration of 36,000 ppm. Report your answer in atm to 2 sig figs: ## atm 31 Π K)(2) K)(300 mol / atm L 82 mol/L)(0.0 (0.64 Π M 0.64 L 970 g) mL/1.03 (1 solutn of g 10 in mol 620 g) mol/58 (1 g 36,000 ppm 36,000 6 2 p. 755 Reverse osmosis is used to convert salt water into fresh water. Requires pressures > 30 atm. Reverse osmosis is used to purify water. Membrane filters are used to purify water. Chemistry research is producing new and better membranes and filters. A reverse osmosis water facility in Israel.

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2 3 Fig. 15-26, p. 760 Producing potable water is a big issue! 4 Chemistry is key to resolving all the BIG GLOBAL ISSUES! Here are some - Energy Photovoltaic collectors Climate Change CO 2 sequestration Photocatalysts Health Enzyme inhibition Potable Water Reverse osmosis membranes Molecular filters
3 5 Use Osmotic Pressure to Determine Molar Mass You are working as an intern in a biochemistry lab. Your advisor just isolated an enzyme and asks you to determine its molar mass using osmosis. You dissolve 5.0 g of the enzyme in water to make 1.0 L of solution. You measure the osmotic pressure, and find it to be 7.6 torr at 298 K. You report that the molar mass is ____________ g/mol. A) between 0 and 1,000 B) between 1,000 and 5,000 C) between 5,000 and 10,000 D) between 10,000 and 20,000 E) between 20,000 and 50,000 = cRTi R = 0.082 L atm mol -1 K -1 Solve for c, multiply by volume to get number of moles, n n = mass/molar mass molar mass = 5.0 g / 4.09x10 -4 mol = 12,200 g/mol 6 Which Salt to Buy for De-icing?

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## This note was uploaded on 02/13/2011 for the course CHE 132 taught by Professor Hanson during the Spring '08 term at SUNY Stony Brook.

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28 Solubility Product Problems - =cRTi R = 0.082 L atm...

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