Solutions Chm 3.2. Solutions Solute – substance dissolving Solute – substance dissolving Solvent...
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Transcript of Solutions Chm 3.2. Solutions Solute – substance dissolving Solute – substance dissolving Solvent...
SolutionsSolutions
Chm 3.2Chm 3.2
SolutionsSolutions
Solute – substance dissolvingSolute – substance dissolving
Solvent – substance solute is Solvent – substance solute is dissolved indissolved in– (substance you have in greatest (substance you have in greatest
amount)amount)
Solution – solvent + soluteSolution – solvent + solute
Types of SolutionsTypes of Solutions
Solids – alloys (metal mixtures)Solids – alloys (metal mixtures) Liquids – sugar or salt in waterLiquids – sugar or salt in water Gases – airGases – air Suspensions – solute particles so large Suspensions – solute particles so large
they settle out (muddy water)they settle out (muddy water) Colloids – solute particles are sized in-Colloids – solute particles are sized in-
between solution and suspensionbetween solution and suspension Homogeneous - solutionsHomogeneous - solutions Heterogeneous – colloids, suspensionsHeterogeneous – colloids, suspensions
Electrolyte vs Non-Electrolyte vs Non-electrolyteelectrolyte
Electrolyte – substance that dissolves Electrolyte – substance that dissolves to form a solution that conducts to form a solution that conducts electricityelectricity
Non-electrolyte – substance that Non-electrolyte – substance that dissolves to form a solution that dissolves to form a solution that DOES NOT conduct electricityDOES NOT conduct electricity
Factors affecting Rate of Factors affecting Rate of DissociationDissociation
Rate depends on Solute/Solvent Rate depends on Solute/Solvent Interactions or AttractionInteractions or Attraction
– Increasing Surface AreaIncreasing Surface Area
– Agitating a SolutionAgitating a Solution
– Heating (more KE = more collisions)Heating (more KE = more collisions)
SolubilitySolubility Solubility has a limitSolubility has a limit Solution equilibrium – opposing processes Solution equilibrium – opposing processes
of dissolution and crystallization occuring of dissolution and crystallization occuring at equal ratesat equal rates
Saturated Solution – contains the max Saturated Solution – contains the max amount of solute amount of solute
Unsaturated Solution – contains less solute Unsaturated Solution – contains less solute than a saturated solutionthan a saturated solution
Supersaturated Solution – more dissolved Supersaturated Solution – more dissolved solute than a saturated solution under the solute than a saturated solution under the same conditionssame conditions
Measuring SolubilityMeasuring Solubility
The amount of substance required to The amount of substance required to form a saturated solution with a form a saturated solution with a specific amount of solvent at a specific amount of solvent at a specific temperaturespecific temperature
Solubility varies with temperatureSolubility varies with temperature Rate of a solid dissolving is not Rate of a solid dissolving is not
related to solubilityrelated to solubility
Dissolving Ionic Compounds in Dissolving Ionic Compounds in Water (Hydration)Water (Hydration)
Polar water attracts + and – ionsPolar water attracts + and – ions Water molecules surround ionsWater molecules surround ions Ions are drawn away from surface of Ions are drawn away from surface of
the crystalthe crystal HydratesHydrates
– Some ionic compounds will re-crystallize Some ionic compounds will re-crystallize with water molecules attachedwith water molecules attached
CuSOCuSO44 · 5H· 5H22OO
Like Dissolves LikeLike Dissolves Like
Polar dissolves in polarPolar dissolves in polar Non-polar DOES NOT dissolve in polarNon-polar DOES NOT dissolve in polar
Immiscible – Immiscible – – Liquid solvents and solute that are not Liquid solvents and solute that are not
solublesoluble Miscible – Miscible –
– Liquids that dissolve freely in eachotherLiquids that dissolve freely in eachother
Gas SolubilityGas Solubility
PressurePressure– Increasing pressure = stress on EQIncreasing pressure = stress on EQ– More molecules collide with surface of More molecules collide with surface of
liquidliquid– EQ shifts so fewer molecules are in gas EQ shifts so fewer molecules are in gas
phasephase– Increases solubilityIncreases solubility– Henry’s LawHenry’s Law – – solubility of gas is directly solubility of gas is directly
proportional to pressure of the gas on proportional to pressure of the gas on surface of liquidsurface of liquid
Temperature and SolubilityTemperature and Solubility
Gas Solubility in LiquidsGas Solubility in Liquids– Increase temperature = less gas Increase temperature = less gas
dissolveddissolved
Solid Solubility in LiquidsSolid Solubility in Liquids– Increasing temperature increases Increasing temperature increases
solubility in SOME casessolubility in SOME cases
Concentration of SolutionsConcentration of Solutions
MolarityMolarity
moles of solute per liter of solutionmoles of solute per liter of solution
n
LM =
Molarity ExamplesMolarity Examples
1.1. You have 3.50L of solution that contains You have 3.50L of solution that contains 90.0g of sodium chloride. What is the 90.0g of sodium chloride. What is the molarity of the solution?molarity of the solution?
2. You have 0.8 L of a 0.5 M HCl solution. How 2. You have 0.8 L of a 0.5 M HCl solution. How many moles of HCl does this solution many moles of HCl does this solution contain?contain?
3. What volume of a 6.0M potassium chromate 3. What volume of a 6.0M potassium chromate solution is needed to ensure that 23.4g of solution is needed to ensure that 23.4g of potassium chromate are in the solution?potassium chromate are in the solution?
DilutionDilution
DilutingDiluting– Taking a solution of one concentration and Taking a solution of one concentration and
adding solvent to lower the concentrationadding solvent to lower the concentration
MM11VV11 = M = M22VV22
The concentration x volume of initial The concentration x volume of initial solution is equal to the concentration x solution is equal to the concentration x volume of the final solution. volume of the final solution.
Dilution
water (solvent) solute
concentrated, Minitial
diluted, Mfinal
adding water lowers the solute concentration
moles of solute remain constant
Vinitial
Vfinal
molesinitial = molesfinal
Mfinal x Vfinal = Minitial x Vinitial
Dilution ExamplesDilution Examples
1.1. What volume of a 5.0 M stock HCl What volume of a 5.0 M stock HCl solution is needed to produce 1.5L solution is needed to produce 1.5L of a 2.5M HCl solution?of a 2.5M HCl solution?
2.2. What will the new concentration be What will the new concentration be when a 0.3 M solution of NaOH is when a 0.3 M solution of NaOH is diluted from 1.0 L to 2.5 L?diluted from 1.0 L to 2.5 L?
Colligative PropertiesColligative Properties
Properties of solutions that depend Properties of solutions that depend on the concentration of solute on the concentration of solute particles dissolvedparticles dissolved
1.1. Vapor Pressure LoweringVapor Pressure Lowering
2.2. Freezing Point DepressionFreezing Point Depression
3.3. Boiling Point ElevationBoiling Point Elevation
4.4. Osmotic PressureOsmotic Pressure