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Published byHilary Haynes Modified over 9 years ago
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SOLUTIONS
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Type of homogenous mixture Has the same composition, color and density throughout Composed of: Solute – substance that is being dissolved Solvent- substance that is doing the dissolving Most common solution – solid in liquid Solutions can also occur between: solid- solid gas - liquid
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SOLID IN LIQUID SOLUTIONS Solute- solid Solvent – liquid usually water- universal solvent Examples: fruit drinks sports drinks Dissolution occurs are the surface of the solid 1) water molecules (polar) surround the solid molecules with their negative ends attracted to the positive ends of the solid 2) water molecules then pull the solid into solution 3) solid molecule and water molecules mix evenly
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OTHER SOLUTIONS Gas-Gas Solutions ex: air Liquid – liquid Solutions Ex: lemonade; mango juice liquids are more freely moving and thus can mix together Solid-Solid Solutions (alloys) Ex: Bronze ( Copper and tin) Sterling Silver Brass Solids must first be melted and then mixed together because of the crystalline shape of solids
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RATE OF DISSOLVING Techniques to speed up the rate of dissolution 1)Stirring – this brings more fresh solvent into contact with solute polarity of both solute and solvent makes solute dissolve faster 2) Crystal size- make large crystals smaller this makes the surface area larger—because dissolution occurs at surface area of the solid increasing surface area allows more solvent to come into contact with solute 3) Temperature- increasing temperature increases molecular movement of solvent Controlling the Process- Combination of two of the above techniques increases dissolution even more
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SOLUBILITY Maximum amount of a solute that can be dissolved in a given amount of solvent at a given temperature Concentrated solutions- large amount of solute is dissolved in the solvent Diluted solutions - small amount of solute is dissolved in the solvent Solubility of common substance in 100 g of water at 20°C: salt 35.9 baking soda 9.6 sugar 203.9 hydrogen 0.00017 carbon dioxide 0.16
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TYPES OF SOLUTIONS Saturated Solutions: Solution that contains all the solute a solvent can hold at a given temperature Unsaturated Solutions: Solution that dissolve more solute at a given temperature Supersaturated Solutions: Solution that contains more solute than a saturated solution This solution is very unstable---- energy is given off
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SOLUBILITY CURVE Rule of Thumb for reading the solubility curve: Unsaturated – below the curve Saturated - is the curve Supersaturated – above the curve
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SOLUBILITY OF GASES Increasing Solubility: 1) Pressure - Increasing pressure increases the amount of gas dissolved in liquids reason why soda fizzes when popped 2) Temperature - cooling the solvent increases the amount of gas that dissolves reason why soda gets warm when top is popped- more CO 2 has escaped
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PARTICLES IN SOLUTION Electrolytes – compounds that produce solutions of ions that conduct electricity Ex: NaCl – stong electrolyte conducts strong current exist completely as ions in solutions Acetic Acid – weak electrolyte conducts weak current exist as molecules in solutions Nonelectrolytes – compounds that do not produce solutions of ions Ex: sucrose and ethyl alcohol
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PARTICLES IN SOLUTION Two Ways to produce ionic compounds 1)Ionization – production of charged particles (ions) ex: HCl 1)Dissociation – separation of positive and negative particles from ionic crystals ex: NaCl -- NaCl crystals will break apart under the influence of water -- Na and Cl pull apart (dissociate) and move freely in solution -- Na and Cl ions can now produce an electric current
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SOLUTE EFFECT ON SOLVENT Lowers the freezing point of the solvent - solute interferes with the formation of particle arrangement ex: antifreeze Raises the boiling point of the solvent - solute interferes with the evaporation of solvent particles - more energy is needed for solvent particles to change phase from liquid to gas ex: car radiators
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NONPOLAR SOLUTES Many solutes do not dissolve in water - there is no distinct dissociation of ions Ex: Vinegar and Oil Polar and Nonpolar Solutes - polar end dissolves polar molecules; nonpolar end dissolves nonpolar molecules Ex: Ethanol - dissolves iodine (nonpolar0 - dissolves water (polar) Useful Nonpolar Molecules: Disadvantages of Nonpolar Molecules: Mineral Oil1) flammable turpentine2) toxic dry cleaner solutions
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SOAPS Salts of fatty acids Hydrocarbons with carboxyl end (-COOH) Contain both polar and nonpolar properties The making of soaps: H of the acid group is removed leaving a negative charge K or Na ion left with positive charge The ionic nature of the acid dissolves in water The hydrocarbon end dissolves in oils
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VITAMINS Vitamin A – nonpolar molecule that dissolves in fats Vitamin B – polar molecule that dissolves in water Vitamin C – polar molecule that dissolves in water Nonpolar molecules can accumulate in the body and become toxic Polar molecules do not accumulate in the body—excess is removed in urine
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