Solubility Rules Solubility Rules & Reference Tables& Reference Tables

Components of a SolutionComponents of a Solution

SoluteSolute: substance : substance being dissolvedbeing dissolved

Ex: Salt, SugarEx: Salt, Sugar

Solvent:Solvent: substance substance doing the dissolvingdoing the dissolving

Ex: Water, HexaneEx: Water, Hexane

SolubilitySolubility:: How muchHow much solute can solute can

dissolve under certaindissolve under certain

conditions ofconditions of

temp. and pressure.temp. and pressure.

Factors Affecting Factors Affecting SolubilitySolubility

Surface AreaSurface Area

More solute/solvent contactMore solute/solvent contact

means faster dissolvingmeans faster dissolving

Crush substance into fineCrush substance into fine

powderpowder

Use mortar and pestleUse mortar and pestle

Stirring or Agitation:Stirring or Agitation:

More solute/solventMore solute/solvent

contact (solids/liquids)contact (solids/liquids)

However, stirring disturbsHowever, stirring disturbs

dissolved dissolved gasesgases and they and they

come come out of solution.out of solution.

Temperature of SolventTemperature of Solvent

Higher temperatures will allow more Higher temperatures will allow more

solid solutessolid solutes to dissolve to dissolve

GasesGases dissolve better when dissolve better when

solvent temperature is solvent temperature is colder.colder.

Ex: Ex: COCO22 gas in hot soda (flat) gas in hot soda (flat)

vs. cold soda (fizzy)vs. cold soda (fizzy)

PressurePressure

Effects Effects gasgas solubility only solubility only

Why?Why?

Increasing pressure onIncreasing pressure on

a gas above a liquida gas above a liquid

causes more gascauses more gas

molecules to bemolecules to be

““pushed” into solution.pushed” into solution.

Ex: COEx: CO22(aq) in soda(aq) in soda

Nature of Solute and SolventNature of Solute and SolventPolar solutes dissolve in polar solventsPolar solutes dissolve in polar solvents

Nonpolar solutes dissolve in nonpolar Nonpolar solutes dissolve in nonpolar solventssolvents

Most ionics (but not all) dissolve in polar Most ionics (but not all) dissolve in polar solvents (molecule-ion attractions)solvents (molecule-ion attractions)

Amount of Solute already DissolvedAmount of Solute already Dissolved

As particles dissolve in solution fewerAs particles dissolve in solution fewer

solvent molecules are available to dissolvesolvent molecules are available to dissolve

new solute.new solute.

Miscible:Miscible:

2 liquids that dissolve2 liquids that dissolve

(ex: alcohol and water)(ex: alcohol and water)

Immiscible:Immiscible:

2 liquids that 2 liquids that do notdo not dissolve (ex: oil and water)dissolve (ex: oil and water)

Electrolytes:Electrolytes: Conduct electricity when dissolved in waterConduct electricity when dissolved in water

Why do they Conduct?Why do they Conduct?

Create Create mobile ions in solutionmobile ions in solution..The more concentrated the solution the The more concentrated the solution the

more it conductsmore it conducts

Includes:Includes:Soluble Ionic Compounds (ex: NaCl)Soluble Ionic Compounds (ex: NaCl)Acids (ex: HCl)Acids (ex: HCl)Bases (ex: NaOH)Bases (ex: NaOH)

Who Will Conduct?Who Will Conduct? Which of the following compounds will conduct Which of the following compounds will conduct

in solution? (ionic salt, acid, base?)in solution? (ionic salt, acid, base?) See Ref Tables for common acids/basesSee Ref Tables for common acids/bases

CC66HH1212OO66 LiBrLiBr KOHKOH CHCH44 HH22SOSO44 NONO22

CC66HH1212OO66 Will NotWill Not (Covalent) (Covalent) LiBrLiBr Will (Ionic)Will (Ionic)KOHKOH Will (Base)Will (Base)CHCH44 Will NotWill Not (Covalent) (Covalent)

HH22SOSO44 Will (Acid)Will (Acid)

NONO22 Will NotWill Not (Covalent) (Covalent)

Using Reference Table GUsing Reference Table G

Shows solubility in Shows solubility in grams of solute per grams of solute per 100 grams of water at 100 grams of water at different tempsdifferent temps

Saturated Solutions:Saturated Solutions:

hold max solutehold max solute

possible at that temp.possible at that temp.

Table G: Table G:

Solubility curve linesSolubility curve lines

show saturation levelsshow saturation levels

at different tempsat different temps

Saturated Solutions are at Saturated Solutions are at EQUILIBRIUMEQUILIBRIUM..

Rate of dissolving = Rate of crystallizationRate of dissolving = Rate of crystallization

Ex: How many grams Ex: How many grams of NaNOof NaNO33 are needed are needed

to create a sat. to create a sat. solution in 100g of solution in 100g of water at 50 water at 50 °°C?C?

Go to 50 Go to 50 °°C and up to C and up to NaNONaNO33 and over. and over.

Answer: 116 gramsAnswer: 116 grams

Look at The Water!!Look at The Water!!

Table G is for 100 grams of water.Table G is for 100 grams of water.

Amount of water in your problem may be Amount of water in your problem may be different and you need to adjust your different and you need to adjust your answer.answer.

How many grams of NaNOHow many grams of NaNO33 are needed to are needed to

create a sat. solution in create a sat. solution in 300g of water300g of water at 50 at 50 °°C?C?

Answer: Answer: 116 grams x 3116 grams x 3 (three times as much (three times as much water!)water!)

Or you can use a proportion:Or you can use a proportion:

116 grams116 grams == x gramsx grams

100 g H100 g H2200 300g H300g H2200

Unsaturated SolutionsUnsaturated Solutions

could still hold morecould still hold more

solute at that temp.solute at that temp.

Would fall “below the line”Would fall “below the line”

on Table Gon Table G

Ex: Ex: 40 g of NaNO40 g of NaNO33 in in

100g water at 50100g water at 50°°

Supersaturated SolutionsSupersaturated Solutions

hold more solute than theyhold more solute than they

should at that temp.should at that temp.

Would fall “above the line”Would fall “above the line”

on Table Gon Table G

Ex: Ex: 140 g of NaNO140 g of NaNO33 in in

100g water at 50100g water at 50°°

How do Supersaturated Solutions How do Supersaturated Solutions Form?Form?

Create a saturated solution at Create a saturated solution at a high temp. and slowly let a high temp. and slowly let solution cool. solution cool.

Certain solutes can stay in Certain solutes can stay in solution. solution. Ex: sodium acetateEx: sodium acetate

Supersaturated solutions are Supersaturated solutions are unstableunstable. . Add just one more “seed Add just one more “seed

crystal”, all excess solute will crystal”, all excess solute will precipitate leaving a saturated precipitate leaving a saturated solution behindsolution behind

Supersaturated Sodium Acetate solution after seed crystal added

Describe These SolutionsDescribe These Solutions

Saturated, Unsaturated or Supersaturated?Saturated, Unsaturated or Supersaturated?

100 g NH100 g NH44Cl at 70Cl at 70°° in in

100 g water100 g water

Falls above the line Falls above the line (Supersaturated)(Supersaturated)

10g SO10g SO22 at 10 at 10°° in 100g in 100g

waterwater

Falls below the line Falls below the line (Unsaturated)(Unsaturated)

40g NaCl at 9040g NaCl at 90°° in 100g in 100g

waterwater

Falls on the line Falls on the line (Saturated)(Saturated)

Concentrated Solutions:Concentrated Solutions:

have a lot of solutehave a lot of solute

dissolved in the solventdissolved in the solvent

Ex: Saturated solution of Ex: Saturated solution of KIKI

at 10at 10°°

135 grams in 100 g water 135 grams in 100 g water = pretty concentrated= pretty concentrated

Dilute Solutions:Dilute Solutions: only only

have a little solutehave a little solute

dissolved.dissolved.

Ex: Sat. solution of SOEx: Sat. solution of SO22

at 50at 50°°

4 grams in 100 g water 4 grams in 100 g water = relatively dilute= relatively dilute

If Temp. ChangesIf Temp. ChangesHow much will How much will

precipitate out of precipitate out of solution if a solution if a saturated NaNOsaturated NaNO33

solution at 60solution at 60° is ° is cooled to cooled to 2020°° ? ?

Reference Table FReference Table F

Describes which ionic compounds are Describes which ionic compounds are soluble or insoluble in water.soluble or insoluble in water.

Certain combinations of ions hold together Certain combinations of ions hold together so strongly that water cannot dissolve so strongly that water cannot dissolve them into solution (insoluble)them into solution (insoluble)

Is this soluble or not?Is this soluble or not? CaCOCaCO33

Carbonate (COCarbonate (CO33-2-2) is insoluble and Ca) is insoluble and Ca+2+2 as as

a partner is not an exceptiona partner is not an exception

Is this soluble or not?Is this soluble or not? NaNONaNO33

Nitrate (NONitrate (NO33-1-1) is always soluble, there are ) is always soluble, there are

not exceptionsnot exceptions

Is this soluble or not?Is this soluble or not? LiLi33POPO44

Phosphate (POPhosphate (PO44-3-3) is insoluble, however, ) is insoluble, however,

LiLi+1+1 is a Group 1 ion so it is is a Group 1 ion so it is an exceptionan exception and the compound is soluble.and the compound is soluble.

Soluble or Not?Soluble or Not?

Look out for exceptions!Look out for exceptions!CaSOCaSO44

MgSOMgSO44

PbCrOPbCrO44

LiLi22SS

NHNH44OHOH

InsolubleInsoluble CaSOCaSO44

SolubleSoluble MgSOMgSO44

InsolubleInsoluble PbCrOPbCrO44

SolubleSoluble LiLi22SS

SolubleSoluble NHNH44OHOH

PrecipitatesPrecipitates

PrecipitatesPrecipitates are are insolubleinsoluble ionic compounds formed in ionic compounds formed in double replacement reactions.double replacement reactions.

Determine which product is the Determine which product is the insoluble precipitate by using insoluble precipitate by using Table F.Table F.

When a precipitate forms, When a precipitate forms, you create a heterogeneous you create a heterogeneous mixture. mixture.

You can separate a You can separate a precipitate by precipitate by filtrationfiltration..

The solid will stay on the The solid will stay on the paper.paper.