PowerPoint Presentation

Unit Eleven: Solutions

1SolutionsA solution is a homogeneous mixture of two or more substancesHomogeneous uniform characteristics throughoutHeterogeneous different compositions; various throughout

Solutions have at least two componentsSolutes the minority componentSolvents the majority component

75% isopropyl solution solute is water, solvent is isopropyl3% H2O2 solute is H2O2, solvent is water

2Nine types of mixturesSoluteSolventExamples**GasGasAir**GasLiquidSodaGasSolidStyrofoam or marshmallowsLiquidGasClouds**LiquidLiquidAlcohol in waterLiquidSolidMercury on penny (amalgam)SolidGasSmoke**SolidLiquidSugar or salt in water (Liquid is usually solvent)**SolidSolidCoins, gemstones, alloys- ** means common type of solutionAmalgam: an alloy of mercury and another metalLikes Dissolves Likes3Non-Solutions - SuspensionsSuspensions

A mixture from which particles settle out upon standing

Particles are larger than in a solution

Suspended temporarily out of school

Examples: Italian Dressing, muddy water, orange juice with pulp4Non-Solutions - ColloidsColloidsA permanent mixture whose particles are smaller than in a suspension and larger than in a solution

Particles will reflect light, cloudy appearance

Do not settle out and cannot be filtered

Milk, starch, dusty air, fog5NameParticle SizePermanenceExamplesSolutiond < 1 nmPermanentSugar-water, acids, bases, salt waterColloid1 nm < d < 100nmPermanentMilk, blood, mayonnaiseSuspensiond > 100 nmSettles OutMud, clay, cementPropertySolutionsColloidsSuspensionsSettling OutDo not settleDo not settleSettle on standingFilteringUnchangedUnchangedSeparates when filteredTyndall EffectDo not scatter lightScatters lightScatters lightEffect on Colligative PropertiesDoes affectDoes not affectDoes not affect6Tyndall EffectLaser pointed through a solution, colloid, and suspension what will happen?7Non-ElectrolyteAqueous solutions containing a solute that dissolves as molecules

Do not conduct electricity

CH3OH CH3OH

C12H22O11 C12H22O118ElectrolyteAqueous solutions containing a solute that dissociates into ions

Conducts electricity

NaCl Na1+ + Cl1- or Al2(SO4)3 2Al3+ + 3SO42-

Strong electrolytes have large portions of solute existing as ions

Weak electrolytes have a fraction of the solute existing as ions9SolubilitySolubility is the amount of compound (usually in grams) that will dissolve in a certain amount of liquid

There are three types of solutions:UnsaturatedSaturatedSupersaturated 10SolubilitySaturated SolutionsHold the maximum amount of solute under the solution conditions

If additional solute is added to a saturated solution, it will not dissolve

Unsaturated SolutionsHold less than the maximum amount of solute under the solution conditions

If additional solute is added to an unsaturated solution, it will dissolve

Supersaturated SolutionsHold more than the normal maximum amount of solute

Any disturbance will precipitate the solute or make it come out of solution

11Supersaturated Solution

Example: Rock Candy12Solubility Curves35 grams of NaCl per 100 grams at 25C is a __ soln.

25 g of KNO3 per 35 g of water at 50C is a ___ soln.

45 g of KNO3 per 100 g of water is cooled from 40C to 0C

13SolubilitySolubility depends on:Identity of solute and solventLike dissolves like -> polar dissolves polar and nonpolar dissolves nonpolar

TemperatureFor solids in liquids, solubility increases with increasing temperature

For gases in liquids, solubility decreases with increasing temperature14SolubilityPressureFor solids in liquids, a change in pressure has very little effect on the solubility

For gases in liquids, higher pressure increases the solubility of the gas in the liquid

When a can of soda is opened, there is less pressure so the gas is less soluble

15Worksheet One is due Friday (Tomorrow)

Worksheet Two is due MondaySkip Question 10Questions 3, 4, and 5 you cannot answer until Fridays notes16SolubilityRate of solution How fast a substance dissolves and how quickly the substance goes into solution

Factors that increase the rate of solution for solidsDecrease particle sizeStirringIncrease temperature17Hydration versus SolvationHydration

A solute is dissolved by water molecules attaching to ions and moving them into solution

Solvation

Process of molecules of a solvent moving molecules or ions into solution

18ConcentrationsConcentrations the amount of solute in a solutionA dilute solution is one containing small amounts of solute relative to solvent

A concentrated solution is one containing large amounts of solute relative to solvent

Mass percent, molarity, and molality19Mass PercentsMass Percents the number of grams of solute per 100 grams of solution

Mass percent=(mass of solute)/(mass of solution)x100

20Practice ProblemsCalculate the mass percent of NaCl in a solution containing 15.3 grams of NaCl and 155.0 grams H2O.

Calculate the mass percent of a solution containing 27.5 grams C2H6O and 175 mL of H2O

A soft drink contains 11.5% sucrose by mass. What volume of soft drink solution, in mL, contains 85.2 grams of sucrose?21MolarityMolarity the number of moles of solute per liter of solution

A concentration of 6 M HCl contains 6 moles of HCl per 1 L of solution

Molar solutions are prepared in a volumetricflask

Molarity = M = moles of solute/liters of solution

22Practice ProblemsCalculate the molarity of a sucrose solution made with 1.58 moles of solute diluted to a total volume of 5.0 L of solution.

Calculate the molarity of a solution made by putting 15.5 grams of NaCl into a beaker and adding water to make 1.50 L of NaCl solution.23Practice problems6.7 grams of NH4Cl is dissolved in enough water to make 803 mL of solution. What is the molarity of the solution.

How many grams of NaOH are needed to make 500.0 mL of a 1.00 M solution?

What volume of a 1.0 M NaNO3 solution can be prepared from 170.0 grams of NaNO3?24Solution DilutionsMost solutions are bought as stock solutions, however most labs need diluted solutions.

We use M1V1=M2V2

25Practice ProblemsA laboratory procedure calls for 5.00 L of a 1.50 M KCl solution. How should you prepare this solution from a 12.0 M stock solution?

To what volume should you dilute 0.100 L of a 15 M NaOH solution to obtain a 1.0 M NaOH solution?26Practice ProblemsHow much 6.0 M NaNO3 solution should be used to make 0.585 L of a 1.2 M NaNO3 solution?

27Solution StoichiometryTying it all together!

How much 0.125 M NaOH solution is required to completely neutralize 0.225 L of 0.175 M H2SO4 solution?

H2SO4(aq) + 2 NaOH(aq) Na2SO4(aq) + 2 H2O(l)28Solution StoichiometryHow much 0.115 M KI solution in liters is required to completely precipitate the lead in 0.104 L of 0.225 M Pb(NO3)2?

2 KI(aq) + Pb(NO3)2(aq) PbI2(s) + 2 KNO3(aq)29Solution StoichiometryHow many milliliters of 0.112 M Na2CO3 are necessary to completely react with 27.2 mL of 0.135 M HNO3 according to the following reaction?

2HNO3(aq)+ Na2CO3(aq) H2O(l)+ CO2(g)+ 2NaNO3(aq)30MolalityMolality is the number of moles of solute per kilograms of solvent

A concentration of 6 m HCl contains 6 moles of HCl per 1 kg of solvent

To make 1 liter of 1 m solution, one mole is added to enough water to make 1 L

Which is more concentrated 1.0 m or 1.0 M?1.0 M

Molality = m = moles of solute/kg of solvent32Practice ProblemsWhat is the molality of the solution if 5.0 grams of KI are in 500.0 grams of water?

How many grams of calcium nitrate (Ca(NO3)2) must be added to 20.0 grams of water to make a 2.5 m solution?33Colligative PropertiesA property that depends on the number of solute particles and not the type of solute particles

How much you have not what you have

Two typesFreezing point depressionBoiling point elevationThese depend on quantity of solute not type of solute34

35Colligative PropertiesFreezing point depression difference in temperature between the freezing point of a solution and the freezing point of the pure solvent

Solute disrupts the formation of the orderly pattern thus requiring more energy

Solution freezes at a lower temperature than the pure solvent

Magnitude is proportional to the number of solute particles dissolved36Tf = Kf m (# of particles)Tf = change in temperature

Kf = molal freezing point depression constant

m = molality

(# of particles) = how many particles of solute form in solution37Colligative PropertiesBoiling point elevation difference in temperature between the boiling point of a solution and the boiling point of the pure solvent

Nonvolatile solute dissolved in the solvent disrupts the vapor pressure which increases the boiling point

Solution boil at a greater temperature than the pure solvent

Magnitude is proportional to the number of solute particles dissolved38Tb = Kb m (# of particles)Tb = change in temperature

Kb = molal boiling point depression constant

m = molality

(# of particles) = how many particles of solute form in solution39Practice ProblemsWhat is the freezing point depression and the boiling point elevation of a pinch of salt (0.25 grams NaCl) in a 2.00 L aqueous solution?

Kf=1.86C/m Kb=0.512C/m40Practice ProblemsWhat is the freezing point depression and boiling point elevation of a 0.40 m solution of sucrose in ethanol?

Kf=1.99C/m Kb=1.22C/m

F.p.=-114.6C B.p.=78.4C41Unit Eleven Test Tomorrow (Friday March 8th)

Worksheet Five due Tomorrow

Gizmos due Tomorrow

Lab Report Revisions due TuesdayWill have optional computer time on Monday