SolutionsSolutions

SOLUTE + SOLVENT SOLUTION

State of MatterState of Matter

homogenous mixture of gases (Air…)

Gas:Gas:

solvent: liquid solute: liquid(ethanol in water)

solvent: liquid solute: gassolid

(soda water: CO2/H2O; brine: NaCl/H2O)

Liquid:Liquid:

solvent: solid solute: liquid(Dental-filling alloy)

solvent: solid solute: solid(gold-silver alloy)

Solid:Solid:

Dissolve: solute + solvent solution.

Crystallization: solution solute + solvent.

Saturation: crystallization and dissolution are in equilibrium.

Solubility: amount of solute required to form a saturated solution.

Supersaturated: a solution formed when more solute is dissolved than in a saturated solution.

Miscible: two liquids that mix.

Immiscible: two liquids that do not mix.

Terms to Know…

Like Dissolves Like

“Rule”: polar solvents dissolve

polar solutes. Non-polar solvents

dissolve non-polar solutes. Why?

If ΔHsoln is too endothermic a

solution will not form.

NaCl in octane (C8H18): the ion-

London forces are weak because

octane is non-polar. Therefore,

the ion-London forces do not

compensate for the separation of

ions.

NaCl dissolves nicely in water.

+ –+–

+ –

+ –+–

+ –

NaCl

octane

water

Terminology:

Solubility: is the maximum amount of the solute that will dissolve in a definite amount of solvent (at a given t°)

g/100 mL

Concentration: ratio of the solute and the solvent

Dilute solutionsConcentrated solutions

Saturated solutions:

solutepure solute dissolved

Supersaturated solutions:

g/100 mL KNO3

PbCl2

NaCl

Solubility curves t°

Temperature Effects: Solids

• Experience tells us that sugar dissolves better in warm water than cold.

• As temperature increases, solubility of solids generally increases.

• Sometimes, solubility decreases as temperature increases (e.g. Ce2(SO4)3).

Properties of Water

Most abundant liquid

Vital to life

Universal solvent

1. High melting and boiling points

M.p.: 0.0°CB.p.: 100.0°C (0.1 MPa)

Hydrogen Bonding

Special case of dipole-dipole forces.By experiments: boiling points of compounds with H-F, H-O, and H-N bonds are abnormally high.Intermolecular forces are abnormally strong.

-200

-150

-100

-50

0

50

100

150

0 1 2 3 4 5

Period

Bo

ilin

g P

oin

t (d

eg C

)

Group 4

Group 5

Group 6

Group 7

CH4

SnH4

GaH4SiH4

H2O

H2SH2Se

H2Te

Water Molecule

Solutions

Phase Diagram of H2O

The melting point curve slopes to the left because ice is less dense than water.Triple point occurs at 0.0098°C and 4.58 mmHg.Normal melting (freezing) point is 0°C.Normal boiling point is 100°C.Critical point is 374°C and 218 atm.

2. Density

0.0°C (ice) 0.91680 g/cm3

0.0°C (liquid) 0.99984 g/cm3

3.98°C 0.99997 g/cm3

25.0°C 0.99704 g/cm3

3. Surface tension: high

Bottom of meniscus

4. High heat of vaporization

40.70 kJ/mol

5. High heat of fusion

6.02 kJ/mol

6. High specific heat

75.20 kJ/mol

1. Chemically pure water

2. Water of crystallization or hydration

CuSO4 5H2O(s) CuSO4(s) + 5H2O(g)

(CaSO4)2 H2O (plaster of paris)

CaSO4 2H2O (gypsum)

Na2CO3 10H2O

3. Groundwater

CationsCations AnionsAnions

Ca2+ HCO3-, CO3

2-

Na+ OH-

Mg2+ SO42-

K+ Cl-

Fe2+, Fe3+ NO3-

NH4+ F-, PO4

3-

Hard water Soft water

Water Softening

Temporary hard water HCO3

- (bicarbonate) Permanent hard water

Boiling Softening agents precipitation

complex formation Distillation Ion-exchange

Mineral waterThermal water