Acids and Bases

What are acids and bases? Acid – A substance that produces hydronium ions (H3O+) in water. This is done by the substance losing a hydrogen ion (H+) to a water molecule. Strong Acid – an acid that ionizes completely (nearly 100%) in water. Example: HCl + H2O → H3O+ + Cl- Excellent conductors of electricity in solution. Weak Acid – only a small fraction (generally less than 5%) of the molecules ionize in water. Example: HClO + H2O → H3O+ + ClO- Conduct electricity somewhat (weak electrolytes)

Carboxylic Acids (organic acids) – Contain Generally weak acids – lose the H that is bonded to the O. Properties of Acids: Low pH (below 7) Sour taste (example: citric acid)

Bases – Create hydroxide ions (OH-) in aqueous solution Bases – Create hydroxide ions (OH-) in aqueous solution. They either contain OH- or remove H+ from water. Example: Strong Base – Ionizes completely in solution (example: NaOH) Weak Base – small fraction of molecules create OH- in water (Example: NH3) NH3 + H2O → NH4+ + OH- Properties of Bases: High pH (above 7) Taste Bitter Feel Slippery

Neutralization Reaction A reaction in which an acid and a base react to form water. H3O+ + OH- → 2 H2O 2NaOH + H2SO4 → Na2SO4 + 2H2O KOH + HCl →

pH

pH and pOH pH = -log [H3O+] pOH = - log [OH-] pH + pOH = 14.00 pH of 7 is neutral pH greater than 7 is basic (pOH less than 7) pH less than 7 is acidic (pOH greater than 7) The greater the concentration of hydronium ions, the lower the pH and higher pOH, and vice versa.