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Published byBarry Mills Modified over 9 years ago
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24.1 – How Solutions Form
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Same composition, color, density and taste throughout Homogenous mixture Exist in all states of matter The air we breathe Sterling silver Brass Alloys
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Solute = Substance being dissolved Solvent = Substance doing the dissolving You add a solute to a solvent Solvents and Solutions exist in the same state of matter Aqueous solution = solution with water as the solvent
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Dissolving occurs at the surface Particles are always moving Water molecules are polar They have a positive and a negative end
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Water molecules clusters around the solid molecules with their negative ends attracted to the positive ends of the solids
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Liquids and gases follow the same procedure Solids dissolved in solids melt solid into liquid form then dissolve
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Rates vary by substances Four ways to speed up dissolving 1. Stir the solution 2. Increase temperature 3. Increase pressure 4. Reduce the crystal size
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Surface area – breaking a solid into pieces or a powder increases surface area Dissolving takes place at the surface So more surface area allows for more solvent to come in contact with solute
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The amount of a substance that can dissolve in a solvent Depends on the nature of substances The solubility of two substances can be compared by measuring
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Expressed as a percent by volume of a solvent A concentrated solution has a large amount of solute in the solvent A dilute solution has a small amount of solute in the solvent
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Saturated solution Contains all the solute it can hold at a given temperature As temperature of a liquid solvent increases, the amount of solid solute it can dissolve increase Unsaturated solution Able to dissolve more solute at a given temperature
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Solubility curve Line on a graph used to figure how much solute can dissolve at any temperature on the graph
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Supersaturated solution Contains more solute than a saturated one at the same temperature Made by raising temperature of a saturated solution, adding more solute, and lowering temperature back without disturbing the solution The solution is unstable, it will crystallize if disturbed, giving off energy, and producing heat
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When dissolved in water, it loses at least one hydrogen atom forming hydronium ions (H 3 O + ) Taste sour Are corrosive Can damage skin or tissue React with an indicator (litmus paper) to produce a predictable color change (red)
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Food contains acid – Citrus food = citric acid – Yogurt & buttermilk = lactic acid – Vinegar = acetic acid Stomach uses hydrochloric acid Four acids are vital to industry – Sulfuric acid = car batteries & manufacturing of fertilizers – Phosphoric acid = detergents, fertilizers, and soft drinks – Nitric acid = fertilizers – Hydrochloric acid = used to clean steel
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Forms hydroxide ions (OH - ) in a water solution Or accepts Hydronium ions (H 3 O + ) from acids Feel slippery in solution React with indicators to produce predictable color changes Many are crystalline solids in pure undissolved state Strong bases are corrosive
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Used in cleaning products, medications, fabrics and deodorants
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Process in which an ionic solid separates into its positive and negative ions Acid = (H 3 O + ) Base = (OH - ) and does not combine with water
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A chemical reaction between an acid and a base in water solution H 3 O + + OH - 2 H 2 O
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Acid + Base Salt + H 2 O Salt = negative ion from acid and positive ion from base
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Base that does not contain OH - Forms NH 4 + in H 2 O NH 3 + H 2 O NH 4 + + OH -
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Depends on how completely an acid or base separates into ions when dissolved in water Strong acid = ionizes almost completely Weak acid = only partly ionizes in solution Strong base = dissociates completely Weak base = does not ionize completely
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Strong acids and bases conduct more electricity than weak ones Equations for strong acids and bases use a single arrow indicating ions are formed Equations for weak acids and bases use double arrows pointing in opposite directions indicating an incomplete reaction
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Term used to describe the amount of acid or base dissolved in solution Different from strength Strength = classification Concentration = amount
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Measure of the concentration of H ions in a solution how acidic or basic it is Determined using a universal indicator paper (litmus) or a pH meter pH lower than 7 = acid Strong acid = pH 0-3.0 pH greater than 7 = basic Strong base = pH 10-14 pH exactly 7 = neutral
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