1 Brown, LeMay Ch 13 AP Chemistry CaCl 2 (aq). ExampleSolventSolute Air (g in g) Soda (g in l) H 2 in Pt (g in s) Alcoholic beverages (l in l) Sea water.

1

Brown, LeMay Ch 13AP Chemistry

CaCl2 (aq)

Example Solvent Solute

Air (g in g)

Soda (g in l)

H2 in Pt (g in s)

Alcoholic beverages (l in

l)

Sea water (s in l)

Brass (s in s)

2

N2 O2

H2O CO2

Pt H2

H2O C2H5OH

H2ONaCl

(one of many salts)Copper

(55% – 90%)Zinc

(10% – 45%)

Solutions form (the solute and solvent will mix) when: Energy: solute-solvent interactions are stronger

than solute-solute or solvent-solvent interactions. Disorder: Solutions result in a more disordered

state than the separate solute and solvent states, since molecules will be “mixed” that were once “well organized”.

NaCl (s) + H2O (l) → Na+ (aq) + Cl- (aq) Ion-dipole interactions > H-bonds

(H2O···H2O) < Ionic bonds (Na+ Cl-) The increase in disorder also drives the dissolving

process.http://phet.colorado.edu/en/simulation/soluble-salts3

Molarity: commonly used for solutions

4

solution Liters

solute molM

Varies with T

Partner Activity: How do you make I M 500 mL NaCl solution?

Solvation: dissolving; the interactions between solute and solvent Hydration: solvation with water

Crystallization: “un-dissolving”; process by which solute particles leave the solvent. Solute + solvent ↔ solution

(equilibrium)

5

Endothermic- energy absorbing

Exothermic-energy releasing

Dissociation of Ionic Compounds Dissociation of Covalent Compounds

deionized water + NaCl

+

-

bulb

+

battery

Na+

Cl-

When ionic compounds dissociate and a charge if applied to the solutions

http://www.youtube.com/watch?v=VTmfQUNLlMY

Saturated: a solution that is in equilibrium with undissolved solute (appears as solution and crystals)

Solubility: the amount of solute needed to form a saturated solution

Unsaturated: a solution containing less than the saturated amount (appears as solution only)

Supersaturated: a solution containing more than the saturated amount, yet appears unsaturated.

9

Solubility: go to the temperature and up to the desired line, then across to the Y-axis. This is how many g of solute are needed to make a saturated solution of that solute in 100g of H2O at that particular temperature.

At 40oC, the solubility of KNO3 in 100g of water is 64 g. In 200g of water, double that amount. In 50g of water, cut it in half.

If 120 g of NaNO3 are added to 100g of water at 30oC:

1) The solution would be SUPERSATURATED, because there is more solute dissolved than the solubility allows

2) The extra 25g would precipitate out

3) If you heated the solution up by 24oC (to 54oC), the excess solute would dissolve.

If 80 g of KNO3 are added to 100g of water at 60oC:

1) The solution would be UNSATURATED, because there is less solute dissolved than the solubility allows

2) 26g more can be added to make a saturated solution

3) If you cooled the solution down by 12oC (to 48oC), the solution would become saturated

1. “Like dissolves like.” Miscible: liquids that mix (polar or ionic

solute with polar solvent, or nonpolar with nonpolar)

Immiscible: liquids that do not mix (polar or ionic solute with nonpolar solvent)

Covalent network solids do not dissolve in polar or nonpolar solvents.

13

2. Pressure: does not significantly affect solubility of liquids and solids

Gases: increased P means increased solubility

Henry’s law: Cg = k Pg

Cg = solubility of gas in solution (M)

k = Henry’s law constantPg = partial pressure of gas over solutionhttp://wps.prenhall.com/wps/media/objects/1055/1080459/

media/AABTGZG0.html14

William Henry(1775-1836)

3. Temperature Most solids: increased T means

increased solubility * Exception: Ce2(SO4)3

Gases: increased T means decreased solubility

15

(c) 2006, Mark Rosengarten

Mixtures containing particles intermediate between:A solution (homogeneous, < 10 Å)

andA suspension (heterogeneous, >

2000 Å)

Tyndall effect: scattering of lightseen in a colloid

17

John Tyndall(1820-1893)