Physical properties of solutions:

-1- Types of solutions.

-3- Concentration Units.

-4- Effect of temperature on solubility.

-5- Effect of pressure on Solubility of Gases.

-6- Colligative properties.

A solution is a homogenous mixture of 2 ormore substances

The solute is(are) the substance(s) present in thesmaller amount(s)

The solvent is the substance present in the largeramount

An electrolyte is a substance that, when dissolved inwater, results in a solution that can conduct electricity.

A nonelectrolyte is a substance that, when dissolved,results in a solution that does not conduct electricity.

nonelectrolyte weak electrolyte strong electrolyte

A saturated solution contains the maximum amount of asolute that will dissolve in a given solvent at a specifictemperature.

An unsaturated solution contains less solute than the solventhas the capacity to dissolve at a specific temperature.

A supersaturated solution contains more solute than ispresent in a saturated solution at a specific temperature.

Sodium acetate crystals rapidly form when a seed crystal isadded to a supersaturated solution of sodium acetate.

Factors Affecting Solubility

Glucose (which hashydrogen bonding) isvery soluble in water,while cyclohexane(which only hasdispersion forces) isnot.

Factors Affecting Solubility

• Vitamin A is soluble in nonpolar compounds (likefats).

• Vitamin C is soluble in water.

“like dissolves like”

Two substances with similar intermolecular forces are likelyto be soluble in each other.

• non-polar molecules are soluble in non-polar solvents

CCl4 in C6H6

• polar molecules are soluble in polar solvents

C2H5OH in H2O

• ionic compounds are more soluble in polar solvents

NaCl in H2O or NH3 (l)

The concentration of a solution is a measure of theamount of solute that is dissolved in a givenquantity of solvent.

– A dilute solution is one that contains a smallamount of solute.

– A concentrated solution contains a largeamount of solute.

Quantitative Measurement of Concentrations

Mass Percent (w/w) solid mixtures/ solids in solvents

Mass/Volume Percent (w/v) Medical solutionsg/100mL or g/100cc

Mass/Volume (w/v) mg/mL, g/Liter

Volume Percent (v/v) Liquid in liquid, liquors

Molarity (M)(mol/liter) Chemistry reagents

Parts per million (ppm)mg/liter (if water) wt or vol

Trace amounts in water or air

Concentration Units Continued

M =moles of solute

liters of solution

Molarity (M)

Molality (m)

m =moles of solute

mass of solvent (kg)

What is the molality of a 5.86 M ethanol (C2H5OH)solution whose density is 0.927 g/mL?

m =moles of solute

mass of solvent (kg)M =

moles of solute

liters of solution

Assume 1 L of solution:5.86 moles ethanol = 270 g ethanol927 g of solution (1000 mL x 0.927 g/mL)

mass of solvent = mass of solution – mass of solute

= 927 g – 270 g = 657 g = 0.657 kg

m =moles of solute

mass of solvent (kg)=

5.86 moles C2H5OH

0.657 kg solvent= 8.92 m

What is the molality of a 6.76 M propanol (C3H7OH)solution whose density is 0.88 g/mL?

What is the molality of a 4. 68 M phenol (C6H5OH)solution whose density is 0.91 g/mL?

What is the molality of a 8.90 M Hexanol (C6H13OH)solution whose density is 0.81 g/mL?

What is the molality of a 14.3g of sucrose(C12H22O11)in676g of water?

What is the molality of 7.20moles of ethylene glycol(C2H6O2) in 3546g of water?

Aqueous Solutions of IonicCompounds

The forces causing an ionic solid to dissolve inwater are ion–dipole forces, the attraction of waterdipoles for cations and anions.

The attractions ofwater dipoles for ionspulls the ions out ofthe crystalline latticeand into aqueoussolution

SupersaturationA supersaturated solution is created when a warm,saturated solution is allowed to cool without theprecipitation of the excess solute

Non-ideal Solutions

Ethanol andwater have strongattractions –when mixed, thevolume of 50 mLH2O + 50 mLEtOH is less than100 mL

Parts per ….

Parts per thousand (‰) = mass of solute x 1000‰ total mass of soln

Parts per million (ppm) = mass of solute x 106ppm total mass of soln

Parts per billion (ppb) = mass of solute x 109ppb total mass of soln

Parts per trillion (ppt) = mass of solute x 1012ppt total mass of soln

a) A cube of sugar in cold tea dissolves slowly.b) Granulated sugar dissolves in cold water more quicklythan a sugar cube, especially with stirring.

c) Granulated sugar dissolves very quickly in hot tea.

Molecules in a cold liquid aremoving relatively slowly andtherefore do not have much energy.

Molecules in a hot liquid are movingfast. Fast moving molecules have asignificant kinetic energy.