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Published byMerry Hart Modified over 9 years ago
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Is there a LIMIT to how much solute can dissolve into the solvent?
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Solutions Homogeneous Mixtures
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Solution : Solvent: substance present in a
Greater (Larger) amount Solute: substance that is present in a lesser (Smaller) amount
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“Likes dissolve likes”
Polar dissolves in polar Sugar and water Nonpolar dissolves in non polar crayons and oil
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Molarity (M or mol/L) CONCENTRATION
Mole fraction ( c or mol/ mol total) Molality (m or mol/Kg solvent) Mass percent (% or g/ g total)
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Solutions can be classified as saturated or unsaturated.
Definitions Solutions can be classified as saturated or unsaturated. A saturated solution contains the maximum quantity of solute that dissolves at that temperature.
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Solvation: The attaching of solvent particles to solute particles.
Solvation Process D6 c20 Solvation: The attaching of solvent particles to solute particles.
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Solubility: Maximum amount of solute
SATURATED SOLUTIONS Solubility: Maximum amount of solute per 100 g solvent
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Dissolving Effects: c34 Saturated Solution- maximum amount of solute in solution Any extra solute added just sits on bottom. Unsaturated- less than max. solute than then can be dissolve. Supersaturated- A solution containing more solute than normal for a given temperature. Must heat a saturated solution up. Then return it to room temperature.
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For a Supersaturated solution, when more solute is
added, the extra solute will settle to the bottom
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Supersaturated Sodium Acetate
One application of a supersaturated solution is the sodium acetate “heat pack.” Sodium acetate has an ENDOthermic heat of solution.
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Temperature effects the solubility of a substance
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Solubility Curves How much LiCl will dissolve into 100 ml of water at a temperature of 20 C? How much KCl will dissolve into 500 ml of water at a temperature of 80 C? How much RbCl will fall out of solution if 200 ml of solution is cooled from a temperature of 80 C to 20 C?
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Dissolving Effects Solubility- the quantity of solute that will dissolve in 100 g of solvent at a set temperature If solution is holding the MAX. Amount of solute called saturated Solid ionic compounds: more in with higher temperature Gases: More in at lower temperatures
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SOLIDS GAS
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Dissolving Gases & Pressure
Gas solubility can be changed by both the temperature and PRESSURE. When the can of soda is opened the pressure (Pgas) drops and causes the solubility to decrease.
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Henry’s Law Gas solubility (mol/L) = Sg Sg = kH • Pgas
kH = Henry’s law constants for O2 = x 10-6 M/mmHg When Pgas increases, solubility increases.
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Henry’s Law Sg = kH • Pgas kH for O2 = 1.66 x 10-6 M/mmHg
What is the concentration of oxygen in fresh water when the air pressure is 1 atm? Sg = kH • Pgas kH for O2 = x 10-6 M/mmHg O2 = 21% so 0.21(760 torr) = Pgas Sg = 1.66 x 10-6 M/mmHg • 160 torr = 2.66 x 10-4 M What is the concentration of oxygen in milligrams/ liter? O2 = 8.5 mg/L
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