Ch. 9 - Solutions Solute 溶质 Solvent溶剂

1. Solvation溶剂化 the process of dissolving a.solute particles are surrounded by solvent particles b.particles are separated and pulled into solution

C. Johannesson

Non- Electrolyte Weak Electrolyte Strong Electrolyte 非电解质 弱电解质 强电解质 + sugar - + acetic acid - + salt Non- Electrolyte Weak Electrolyte Strong Electrolyte solute exists as molecules only solute exists as ions and molecules solute exists as ions only DISSOCIATION IONIZATION 非电解质 弱电解质 强电解质

Dissociation separation of an ionic solid into aqueous ions(NaCl) Ionization breaking apart of some polar molecules into aqueous ions (HNO3)

“Like Dissolves Like” NONPOLAR POLAR

2. Solubility溶解度 UNSATURATED SOLUTION more solute dissolves no more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form concentration

Solubility溶解度 maximum grams of solute that will dissolve in 100 g of solvent at a given temperature varies with temperature

溶解度曲线 Solubility Curve shows the dependence of solubility on temperature

T: For many solids dissolved in liquid water, the solubility increases with temperature up. But, as the temperature is raised, gases usually become less soluble in water P: Only for gas phases, the pressure dependence of solubility is significant in practice. The solubility increases with pressure increase. 当压强一定时，气体的溶解度随着温度的升高而减少。这一点对气体来说没有例外，因为当温度升高时，气体分子运动速率加快，容易自水面逸出。 当温度一定时，气体的溶解度随着气体的压强的增大而增大。这是因为当压强增大时，液面上的气体的浓度增大，因此，进入液面的气体分子比从液面逸出的分子多，从而使气体的溶解度变大。

*Soluble and Insoluble a salt can be considered to be "soluble" if more than 1 gram of the salt can be dissolved in 100 milliliters/grams of water. Soluble salts are usually assumed to dissociate completely in aqueous solution. If the solubility is less than 1g/100 ml or g, we call it "insoluble". Salt that are "insoluble" still slightly dissociate in solution to some extent.

Soluble salt: Alkali metals: Li+, Na+, K+, Rb+, Cs+; Ammonium: NH4+; Nitrate: NO3-, perchlorate: ClO4-,

Insoluble salt: SO32- (sulfite), SO42- (sulfate), CO32- (carbonate), PO43- (phosphate), and CrO42- (chromate) salts, except for those containing alkali metals and ammonium, which are soluble. S2- (sulfide) salts, except for those ontaining alkali metals, the alkaline earths, and ammonium, which are soluble. Most hydroxides(OH-) are insoluble,except those of alkali metals and barium.

3. Concentration浓度 The amount of solute in a solution. Describing Concentration % by mass - medicated creams % by volume - rubbing alcohol ppm, ppb - water contaminants molarity - used by chemists molality - used by chemists

（1）Molarity 摩尔浓度 volume of solution

（2）Molality质量摩尔浓度 mass of solvent only 1 kg water = 1 L water

EX. Find the molality of a solution containing 75 g of MgCl2 in 250 mL of water. =3.2m MgCl2

4. Dilution稀释 Preparation of a desired solution by adding water to a concentrate. Moles of solute remain the same.

What volume of 15. 8M HNO3 is required to make 250 mL of a 6 What volume of 15.8M HNO3 is required to make 250 mL of a 6.0M solution? GIVEN: M1 = 15.8M V1 = ? M2 = 6.0M V2 = 250 mL WORK: M1 V1 = M2 V2 (15.8M) V1 = (6.0M)(250mL) V1 = 95 mL of 15.8M HNO3

5. Preparing Solutions 配置溶液 500 mL of 1.54M NaCl mass g of NaCl add water until total volume is 500 mL 45.0 500 mL mark volumetric flask

combine with water until total volume is 250 mL 250 mL of 6.0M HNO3 by dilution measure mL of 15.8M HNO3 95 mL of 15.8M HNO3 95 combine with water until total volume is 250 mL 250 mL mark make the solution up to the calibration mark water for safety

6. Colligative Properties 依数性

（1） Definition定义 properties of solutions that depend on the number of solute particles in a solution, and not on the identity of the particles.

（2）Types Lowering of Vapor Pressure Freezing Point Depression (Tf) f.p. of a solution is lower than f.p. of the pure solvent Boiling Point Elevation (Tb) b.p. of a solution is higher than b.p. of the pure solvent

Raoult’s Law

（3）Calculations计算 T: change in temperature (°C) T= k · m · i T: change in temperature (°C) k: constant based on the solvent (°C·kg/mol) m: molality (m) i: van’ t Hoff Factor

The van ’ t Hoff Factor (i) tells how many ions one unit of a substance will dissociate into in solution. For instance below:

tb = (3.60°C·kg/mol)(3.2m)(1) tb = 12°C b.p. = 181.8°C + 12°C At what temperature will a solution that is composed of 0.73 moles of glucose in 225 g of phenol boil? (kb = 3.60 ℃·kg/mol) （the Boiling Point of pure phenol is 181.8℃ ） GIVEN: b.p. = ? tb = ? kb = 3.60°C·kg/mol WORK: m = 0.73mol ÷ 0.225kg tb = (3.60°C·kg/mol)(3.2m)(1) tb = 12°C b.p. = 181.8°C + 12°C b.p. = 194°C m = 3.2m n = 1 tb = kb · m · n

*Osmotic Pressure 渗透压π 将溶液和水置于U型管中，在U型管中间安置一个半透膜，以隔开水和溶液，可以见到水通过半透膜往溶液一端跑，假设在溶液端施加压强，而此压强可刚好阻止水的渗透，则称此压强为渗透压，渗透压的大小和溶液的摩尔浓度、溶液温度和溶质解离度相关。 范特霍夫公式：πV=nRT或π=MRT → π= iMRT

7.Colloids胶体 A. Colloidal Dispersions (Colloids) 1. Tiny particles suspended in some medium 2. Particles range in size from 1 to 1000 nm. B. Tyndall Effect—Scattering of light by particles a. Light passes through a solution b. Light is scattered in a colloid

气溶胶 气溶胶 泡沫 乳液 溶胶