Solutions Chapter 15

What are solutions? Homogenous mixtures consisting of a solute and a solvent Can be gas-gas, gas-liquid, liquid-liquid, solid-liquid, solid-solid What are examples of solutions?

Solutions Identify the solute and the solvent in the following solutions: –Salt water –Kool-Aid –Gold ring –Dr. Pepper –Vinegar

A substance that dissolves in the solvent is called soluble A substance that will not dissolve in the solvent is called insoluble Two substances that are soluble are called miscible Two substances that are not soluble are called immiscible

Solvation in Aqueous Solutions Like dissolves like –Polar dissolves polar –Non-polar dissolves non-polar Aqueous solutions of ionic compounds –The attractive forces between the ions and water must be stronger than the attraction between the ions

Solvation Animation bowe/sections/projectfolder/flashfiles/ther mochem/solutionSalt.htmlhttp:// bowe/sections/projectfolder/flashfiles/ther mochem/solutionSalt.html ssentialchemistry/flash/molvie1.swf

Solvation of Molecular Compounds Are sucrose (table sugar) and water miscible? Why?

Rates of Solvation How can you make sugar dissolve faster in water? –Agitation – more molecular collisions –Heat – increases kinetic energy –Smaller size – more molecular collisions

Solubility The maximum amount of solute that will dissolve in the solvent –Dependent on temperature –Saturated solution – no more solute can be dissolved in the solvent –Unsaturated solution – more solute can be dissolved in the solveni

Factors that affect Solubility Temperature – most substances are more soluble at higher temperatures Supersaturated solutions –A saturated solution is cooled slowly beyond the normal saturation point –A single crystal or edge will cause the solute to “fall” out of solution Rock candy

1.How does temperature affect the solubility of NH 3 ? 2.How does temperature affect the solubility of KCl?

Factors that affect Solubility Pressure –Affects the solubility of gaseous solutes –Carbonated water is bottled at pressures greater than atmospheric pressure –Henry’s Law – at a given temperature, the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid