2 Mixtures Properties of Mixtures All mixtures share certain properties! mixture = combination of 2 or more substances that are not chemically combinedSubstances that are not chemically combined retain their identity if they don’t react to form a cmpdex: cheese & pizza sauce don’t mix
3 Mixtures Everything in a mixture keeps its properties NO chemical reactions occurs .·. ea substance in mixture has same chemical makeup as beforeMaintains its identityex: pizza, granite have apparent individual components, salt water does notMixtures can be physically separatedDistillation = separates based on boiling pointsMagnet = separation based on magnetismCentrifuge = separates according to densitiesseveral techniques … mix with solvent, filter, evaporation
4 Mixtures Components of a mixtures do not have definite ratios Components don’t need to be combined in definite ratioex: graniteRegardless of ratio, combination is always a mixtureex: still granite!ex: air = mixture composed mostly of N, O, sml amts of CO2, H2O vaporP. 64 Chart!
5 MixturesSolutionsSolution = a mixture that appears to be a single substance but is composed of 2 or more substances that are evenly distributed amongst eachotherThey are often described as homogeneous mixtures b/c they have same appearance and properties throughout the mixture“homo” = sameIn sol’n, solute = substance being dissolved
6 Solvent = substance in which solute is dissolved In sol’n,Solvent = substance in which solute is dissolvedsoluble = solute able to be dissolved in solventinsoluble = unable to dissolve.·. forms a mixture that isn’t homogeneous not a Solute is dissolved in solvent!sol’nIn salt water, which is solute? which is solvent?
7 Sol’ns aren’t limited to liquids! MixturesSol’ns aren’t limited to liquids!When 2 liquids or 2 gases form a sol’n, substance w/ most volume is solvent.Check out p. 65 table!Alloy = solid sol’ns of metals/nonmetals dissolved in metalsex: brass Zn dissolved in Custeel C & other elements dissolved in Fe
8 Particles in sol’ns are extremely small They are so small, they… Don’t scatter lightCan’t be separated by filtrationCan’t see different particlesDon’t settle out
9 MixturesConcentration : How much solute is dissolvedConcentration = measure of amt of solute dissolved in solventunits: solute = g solvent mLKnowing concentration [ %] is v. impt for medicine/chemistry b/c incorrect [% ] can be _harmful or dangerous.
10 sol’ns can be described as concentrated or dilute _________________ = more solute dissolved in equal solvent____________ = less solute dissolved in equal solventNeither specify amt of solute dissolved!MathBREAK
11 Mixtures Solubility: How much solute can dissolve? ex: add too much sugar to lemonade not all will dissolvesolubility (of solute) = amt of solute needed to make saturated sol’n using given amt of certain tempunits: usually expressed in grams of solute per 100 mL of solventThe solubility of (________) at (____) deg C is (____) grams per 100 mL of H2O.
12 Solubility of solid in liquid – positive relationship. MixturesChange of temperatureSolubility of most solids increase as solvent gets heated .·. more solute can higher temp… but this is not the case for all solidsSolubility of solid in liquid – positive relationship.[general rule]
13 Solubility of a gas in liquids decreases as temperature gets higher Solubility of gas in liquid – indirect (negative) relationshipex: bubbles of gas appear in hot H2O before H2O begins to boil gases dissolved in H2O can’t remain dissolved as temp increases b/c solubility of gases is higher tempGRAPH p. 67
14 Solubility of Common Compounds in Water Common compounds that contain the following ions are SOLUBLE.Sodium (Na+), potassium (K+), Ammonium (NH4+)Nitrates (NO3-)Acetates (C2H3O2-), except silver acetate, which is only moderately solubleChlorides (Cl-), except silver, mercury (I), and lead chlorides; PbCl2 is soluble only in hot waterSulfates (SO42-), except barium and lead sulfates; calcium, mercury (I), and silver sulfates are slightly solubleCommon compounds that contain the following ions are INSOLUBLE.Silver (Ag+), except silver nitrate and silver perchlorateSulfides (S2-), except those of sodium, potassium, ammonium, magnesium, barium, and calciumCarbonates (CO32-), except those of sodium, potassium, and ammoniumPhosphates (PO43-), except those of sodium, potassium, and ammoniumHydroxides (OH-), excpet those of sodium, potassium, ammonium, and barium
15 Mixtures Solute… @ given T Where? What happens? Saturated Un-saturated Saturationgiven TWhere?What happens?SaturatedAll solute the solvent can holdON graph lineSolute will sink to bottom if more is addedUn-saturatedSolvent could hold more soluteUNDER graph lineSolute will dissolve if more is addedSuper-saturatedSolvent holds more solute than should holdABOVE graph lineSolute will crystallize if more is added
16 Mixtures What affects how quickly solids dissolve in liquid? Increase rate by…… stirring/shaking solute particles separate and spread out more quickly among solvent… heating solute particles move more quickly due to E increase… crushing increases amt of contact between solute and solvent
17 MixturesSuspensionssuspensions = mixture in which particles of material are dispersed throughout a liquid or gas but are large enough that they settle outOften described as heterogeneous b/c particles are easily seenParticles are …InsolubleFairly large .·. scatter or block lightToo heavy to remain mixed w/o being shaken or stirredSeparation by passing thru filterex: snow globe, Italian dressing
18 MixturesColloidsColloid = mixture in which particles are dispersed throughout but aren’t heavy enough to settle outProperties of both solutions & suspensionsParticles are…Relatively small, but still large enough to scatter lightFairly well mixedDo not settle out .·.Solids, liquids, gases can be used to make colloidsex: milk, mayonnaise, stick deoderant, Jell-O, whipped cream, fogCannot be separated by filtration