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Chemical Solutions. Solution Formation. Whether a substance dissolves depends on… composition of the solute and solvent (think polarity) Rate (speed) of dissolving depends on factors that increase the contact of solvent with the solute temperature (increases speed and amount)
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Solution Formation • Whether a substance dissolves depends on… • composition of the solute and solvent (think polarity) • Rate (speed) of dissolving depends on factors that increase the contact of solvent with the solute • temperature (increases speed and amount) • stirring (only affects speed) • particle size (only affects speed)
Solubility • amount of a substance that dissolves in a given quantity of a solvent at a specified temperature and pressure • expressed in grams of solute per 100 g of solvent (gases in grams per L)
unsaturated solution • more solute can still be dissolved in the solvent at a constant temp. and pressure • saturated solution • the maximum amount of solute is dissolved in a solvent at a constant temp. and pressure • supersaturated solution • contains more solute than it can theoretically hold at a given temperature
miscible • two liquids that dissolve in each other in any proportion • Ex. Water and alcohol • immiscible • liquids that are insoluble in each other in any proportion • Ex. Oil and water
Factors that affect solubility (amount that will dissolve) • temperature affects: • solids, liquid, and gases • solubility increases with temperature for most solids • solubility decreases with temperature for gases
pressure affects: • gasses but not solids • Henry’s Law • at a given temperature, the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquid • as pressure (P) increases = solubility (S) increases-- and vice-versa • S1 / P1 = S2 / P2
Henry’s Law • at a given temperature, the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquid. • as pressure increases = solubility increases S1 / P1 = S2 / P2
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