1. Acids and Bases

2. Arrhenius Definition of Acids and Bases Arrhenius defines acids and bases as: ACID – a substance that dissociates in water to produce H + ions Ex: HCl  H + + Cl - BASE – a substance that dissociates in water to produce OH - ions Ex: NaOH  Na + + OH - Dissociates=breaks into ions

3. Properties of Acids Sour or tart taste Sting open wounds React vigorously with metals Good conductor of electricity (because it contains ions)

4. Properties of Bases Bitter taste Feels slippery Do not react with most metals Good conductor of electricity (because it contains ions)

5. Acid-Base Indicators Indicator – a substance that turns one color in an acidic solution and another color in a basic solution. Common indicators: –Phenolphthalein Clear in acid, pink in base –Litmus paper Red in acid, blue in base

6. Neutralization Reaction Neutralization – the reaction between an acid and a base that produce a salt and water(a salt is not just NaCl, but a number of ionic compounds that crystallize) ACID + BASE  SALT + WATER HCl + NaOH  NaCl + H 2 O acid base salt water

7. Neutralization Continued The H + from the acid and the OH - from the base combine to form water The other elements from the acid and base combine to form a salt

8. H+H+ H + ’s are often referred to as just “protons” because that is all they really are…a proton all by itself!

9. Hydronium Ion, H 3 O + H + = H 3 O + Since H + do not want to be alone, they temporarily attach to H 2 O molecules to make H 3 O +

10. Aqueous Solutions When we use acids and bases, they are always in aqueous solution (meaning they are dissolved in water). The strength of the solution is measured by its concentration. We will study 3 different units of concentration.

11. Solutions Definitions Solution – homogeneous mixture of two or more pure substances Solute – the substance being dissolved Solvent – the substance doing the dissolving (usually water)

12. Equations for Units of Concentrations Molarity (M) = mole solute liters solution Molality (m)= mole solute kg solvent Mole Fraction (X) = mole substance total moles