[birdman11]

The partial pressure of O2 in air at sea level is 0.21 atm. What is the the molar concentration of O2 in the surface water of a mountain lake saturated with air at 20°C and an atmospheric pressure of 686 torr? (At 20°C and a pressure of 1 atm, solubility of O2 is 1.38e-3 M).


A solution containing 82.1 g of ascorbic acid, C6H8O6, dissolved in 210 g of water has a density of 1.22 g/mL at 55°C. What is the molarity of ascorbic acid in this solution?


Find the mass of KNO3, NaCl, and Ce2(SO4)3 required to form a saturated solution in 150 g water at 30°C. (Use this diagram:
http://www.webassign.net/blb8/13-17.gif


Calculate the vapor pressure of water above a solution prepared by dissolving 37.1 g in glycerin (C3H8O3) to 177 g of water at 343 K.


Calculate the mass of ethylene glycol (C2H6O2) that must be added to 1.00 kg of ethanol (C2H5OH) to reduce its vapor pressure by 12.3 torr at 35°C. The vapor pressure of pure ethanol at 35°C is 1.00 multiplied by 102 torr.


Thank you so much in advance for any help.

[macman104]

You need to please show some effort first.  You need to explain what you know, and give us a specific question you have regarding one of the problems.