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 (s in l) Brass (s in s) 2 N2N2 O2O2 H2OH2OCO 2 PtH2H2 H2OH2OC 2 H 5 OH H2OH2O NaCl (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) + H 2 O (l) → Na + (aq) + Cl - (aq)  Ion-dipole interactions > H-bonds (H 2 O···H 2 O) < Ionic bonds (Na + Cl - )  The increase in disorder also drives the dissolving process. 3

 Molarity: commonly used for solutions 4 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

  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 H 2 O at that particular temperature. At 40 o C, the solubility of KNO 3 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 NaNO 3 are added to 100g of water at 30 o C: 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 24 o C (to 54 o C), the excess solute would dissolve.

If 80 g of KNO 3 are added to 100g of water at 60 o C: 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 12 o C (to 48 o C), 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: C g = k P g C g = solubility of gas in solution (M) k = Henry’s law constant P g = partial pressure of gas over solution BTGZG0.html 14 William Henry ( )

3.Temperature  Most solids: increased T means increased solubility  * Exception: Ce 2 (SO 4 ) 3  Gases: increased T means decreased solubility 15

(c) 2006, Mark Rosengarten

 Mixtures containing particles intermediate between:  A solution (homogeneous, < 10 Å) and  A suspension (heterogeneous, > 2000 Å)  Tyndall effect: scattering of light seen in a colloid 17 John Tyndall ( )