24.1 – How Solutions Form. Same composition, color, density and taste throughout Homogenous...
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Transcript of 24.1 – How Solutions Form. Same composition, color, density and taste throughout Homogenous...
24.1 – How Solutions Form
Same composition, color, density and taste throughoutHomogenous
mixture
Exist in all states of matterThe air we breatheSterling silverBrassAlloys
Solute = Substance being dissolved
Solvent = Substance doing the dissolvingYou add a solute to a solventSolvents and Solutions exist in the same state of matter
Aqueous solution = solution with water as the solvent
Dissolving occurs at the surfaceParticles are always moving
Water molecules are polarThey have a positive and a negative
end
Water molecules clusters around the solid molecules with their negative ends attracted to the positive ends of the solids
Liquids and gases follow the same procedure
Solids dissolved in solids melt solid into liquid form then dissolve
Rates vary by substances Four ways to speed up dissolving1. Stir the solution2. Increase temperature3. Increase pressure4. Reduce the crystal size
Surface area – breaking a solid into pieces or a powder increases surface areaDissolving takes place at the surfaceSo more surface area allows for
more solvent to come in contact with solute
The amount of a substance that can dissolve in a solventDepends on the nature of substances
The solubility of two substances can be compared by measuring
Expressed as a percent by volume of a solventA concentrated solution has a large amount of solute in the solvent
A dilute solution has a small amount of solute in the solvent
Saturated solutionContains 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 solutionAble to dissolve more solute at a given temperature
Solubility curveLine on a graph used to figure how much solute can dissolve at any temperature on the graph
Supersaturated solutionContains 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
When dissolved in water, it loses at least one hydrogen atom forming hydronium ions (H3O+)
Taste sour Are corrosive Can damage skin or tissue React with an indicator (litmus paper) to produce a predictable color change (red)
• 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
Forms hydroxide ions (OH-) in a water solutionOr accepts Hydronium ions (H3O+) 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
Used in cleaning products, medications, fabrics and deodorants
Process in which an ionic solid separates into its positive and negative ionsAcid = (H3O+) Base = (OH-) and does not combine with water
A chemical reaction between an acid and a base in water solutionH3O+ + OH- 2 H2O
Acid + Base Salt + H2OSalt = negative ion from acid and positive ion from base
Base that does not contain OH-
Forms NH4+ in H2O
NH3 + H2O NH4+ + OH-
Depends on how completely an acid or base separates into ions when dissolved in waterStrong acid = ionizes almost
completelyWeak acid = only partly ionizes in
solutionStrong base = dissociates completelyWeak base = does not ionize
completely
Strong acids and bases conduct more electricity than weak ones
Equations for strong acids and bases use a single arrowindicating ions are formed
Equations for weak acids and bases use double arrows pointing in opposite directionsindicating an incomplete reaction
Term used to describe the amount of acid or base dissolved in solution
Different from strengthStrength = classificationConcentration = amount
Measure of the concentration of H ions in a solutionhow acidic or basic it is
Determined using a universal indicator paper (litmus) or a pH meterpH lower than 7 = acid
Strong acid = pH 0-3.0pH greater than 7 = basic
Strong base = pH 10-14pH exactly 7 = neutral