Presentation on theme: "I. Characteristics of solutions a. Mixtures and solutions i. Mixtures are either heterogeneous or homogeneous. 1. Heterogeneous mixtures have non-uniform."— Presentation transcript:
I. Characteristics of solutions a. Mixtures and solutions i. Mixtures are either heterogeneous or homogeneous. 1. Heterogeneous mixtures have non-uniform mixing. 2Homogeneous mixtures have uniform mixing.
ii. Homogeneous mixtures can be classified by particle size. 1. In solutions, particles range in size from 0.1-2 nm.
1. In colloids, particles range in size from 2-1000 nm.
iii. When a solid is dissolved in a liquid, the liquid is the solvent and the solid in the solute
b. The solution process. i. Solubility depends on the strength of attraction between solute particles and solvent relative to the attractions in the pure substances
ii. In predicting solubility, polar solvent dissolve polar substances, and nonpolar solvents dissolve nonpolar substances
c. Solubility i. Solubility is a dynamic process 1. When the maximum amount of solute is dissolved in solution, the solution is said to be saturated
2 In a saturated solution, a state of equilibrium is established between the solution and the un-dissolved solute.
1. A solution that contains less than the maximum amount of solute is said to be an unsaturated solution
1. Two liquids are miscible if they dissolve into each other in all portions.
1. When two liquids are insoluble in one another they are said to be immiscible
. The solubility of a substance is the mass of a substance that will dissolve in a given mass of solvent
. Effect of temperature on solubility. 1The solubility of most solid solutes increase in solubility as temperature of the solution increases
1. A solid is more soluble at high temperature than at low temperatures and may form a supersaturated solution when cooled.
3 A supersaturated solution contains more solute that can theoretically hold more at a given temperature.
4 A gas is always less soluble as temperature increases and is more soluble as the temperature decreases.
iv. Effect of pressure on solubility of a gas in a liquid. 1. Increased pressure makes gas molecules more soluble in a liquid
1. Henry’s Law: Relates solubility and pressure above the solution a. The solubility(S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquid.
b. equation: S1/P1 = S2/P2 c. When the pressure of the gas above the liquid increases solubility increases and when the pressure of the gas above the liquid decreases solubility decreases.
II. Quantitative relationships in solutions. a. Concentration i. The concentration of a solution is a measure of the amount of solute that is dissolved in a given amount of solution
ii. Dilute solutions contain a relatively small amount of solute dissolved in solution
iii. Concentrated solutions contain a relatively large amount of solute dissolved in solution.
III. Properties of solutions a. Effects of particles in solution – colligative properties. i. Vapor pressure lowering
i. Vapor pressure lowering. 1. When a solute is dissolved in a pure substance (solvent) the vapor pressure of the solution is always lower than the solvent alone
ii. Boiling point elevation.. 1. When a solute is dissolved in a pure substance (solvent) the boiling point of the solution is always higher than the pure solvent alone.
iii. Freezing point depression. 1. When a solute is dissolved in a pure substance (solvent) the freezing point of the solution is always lower than the pure substance alone.
iv. These effects don’t depend on the identity off the particles. 1. These effects depend on the concentration of the solute. The higher the concentration of solute the greater the temperature will change