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Unformatted text preview: oceans have a higher concentration of disso lved O2 than warm oceans; this affects marine life. 9 Chemistry 101 Chapter 12 II. PRESSURE 1. Solubilit y of Ionic Substances in Water is not affected by pressure changes 2. Solubilit y of Gases in Water Ø is very dependent on pressure changes Ø can be predicted from Henry’s Law
· “The Solubilit y o f a gas in water is direct ly proportio nal to the Partial Pressure of the gas above the aqueous solution” S = KH P where S = solubilit y o f the gas P = partial pressure of the gas KH = Henry’s Law Constant = Constant for: a particular solvent at a given temperature S1 S a P P1 ¾¾ = ¾¾ S2 Formula used to calculate the solubilit y o f a gas if the partial pressure changes P2 SUMMARY IONIC SUBSTANCES Effect of Temperature Effect of Pressure GASES solubilit y generally increases Solubilit y decreases No effect Solubilit y increases Example: o The so lubilit y of carbon dioxide in water is 0.161 g of carbon dioxide in 100 mL of water at 20 C and 1.00 atm. A so ft drink is carbonated with carbon dioxide gas at 5.50 atm. of pressure. What is the solubilit y o f carbon dioxide in water at this pressure ? S1 = 0.161 g/100 mL P1 = 1.00 atm S2 = ? P2 = 5.50 atm 5.50 atm S2 = 0.161 g/100 mL x ¾¾¾¾ = 0.886 g/100 mL 1.00 atm 10 Chemistry 101 Chapter 12 CONCENTRATION UNITS
· The various methods of expressing concentration of a so lut ion are listed below: A given amount of Solute dissolved in a given amount of CONCENTRATION Molarit y mo les so lute/L so l’n M mo les so lute/mo les sol’n unit less Mass Percent SOLVENT SYMBOL Mole Fract ion SOLUTION UNITS g solute / g sol’n) x 100 % w/w Molalit y mo le so lute / Kg solvent m · The interconversio n of units is an important skill in studying the chemistry of so lut ions. Molarity ® % by mass The mo larit y o f a particular brand of vinegar (solution of acet ic acid, HC2H3O2, in water) is 0.8527 M. The densit y o f vinegar is 1.0052 g/mL. Calculate the mass percent o...
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