Solutions, Acids and Bases

Solutions, Solubility and Concentration Solution – mixture that has the same composition, color, density and taste throughout Solute – substance being dissolved Solvent – substance doing dissolving Solutions can also be gaseous, like the air you breathe, or even solid, like brass and sterling silver

Solutions, Solubility and Concentration When forming a solution, there are three ways to speed up the rate of the dissolving process: Stirring – brings more solvent in contact with solute Increase surface area – by breaking up a solid, for instance, by crushing it into a powder, allows more solvent to come in contact with solute Increase temperature – increasing temperature speeds up particles causing them to bump each other, breaking apart and coming in contact with solvent

Solutions, Solubility and Concentration Solubility – maximum amount of a solute that can be dissolved in a given amount of solvent at a certain temperature Concentration – percent by volume of solute in solvent Concentrated – large amount of solute in solvent Dilute – small amount of solute in solvent

Solutions, Solubility and Concentration Types of solutions: Saturated Contains all solute it can hold at given temperature Unsaturated Able to dissolve more solute at given temperature Supersaturated Contains more solute than a saturated one Solution is unstable

Acids, bases and salts Acid – substance that produces hydrogen ions (H+) in solution Four Properties of Acids: Acids taste sour Acids are electrolytes (can conduct electricity in a solution) Acids are corrosive Acids react with indicators to produce a predictable color change

Acids, bases and salts Base – substance that produces hydroxide ions (OH-) in solution; also accepts H+ from acids Also called alkaline Five Properties of Bases: In undissolved state, many bases are crystalline solid In solution, bases feel slippery Bases have a bitter taste Strong bases are corrosive Bases react with indicators

Acids, bases and salts Indicator – organic compound that changes color in the presence of acid or base Ex. Litmus paper Neutralization – chemical reaction between an acid and a base in a water solution that results in formation of salt and water Salt – compound formed when ions of an acid combine with ions from a base

Strength of Acids and Bases The strength of an acid or base depends on how many acid or base particles dissociate into ions in water Strong acid – ionizes almost completely in water Weak acid – only partly ionizes in solution Strong base – dissociates completely in solution Weak base – does not completely dissociate

Strength of Acids and Bases The terms strong and weak refer to the ease in which an acid or base dissociates in a solution Concentration The terms dilute and concentrated are used to indicate the amount of acid or base dissolved in a solution *It is possible to have dilute solutions of strong acids and bases, as well as concentrated solutions of weak acids and bases.

Strength of Acids and Bases pH – measure of concentration of H+ ions in a solution or how acidic or basic it is pH scale typically ranges from 0 - 14 Strong Acid Weak Acid Weak Base Strong Base

Strength of Acids and Bases