Acids & Bases

Acids and Bases Goals A. Explain the structure of the pH scale. B. Compare and contrast the components and properties of acids and bases. C. Determine whether common household substances are acidic, basic, or neutral.

The pH Scale pH comes from the Greek word potenz meaning power (and H for hydrogen). Measurement system that indicates the number of H+ ions in solution.

NaOH  Na+ + OH- HCl  H+ + Cl- Acids are molecules that release hydrogen ions in solution. HCl  H+ + Cl- Bases are molecules that either take up hydrogen ions or give off hydroxide ions in solution. A strong acid, such as hydrochloric acid, dissociates completely. NaOH  Na+ + OH-

Characteristics of Acids pH less than 7 Produces hydrogen ions (H+) in solution. When added to water H+ interacts with the H2O to produce H30 + (Hydronium ion) Taste sour Corrosive Look at page 767. What do all of the acids have in common?

Characteristics of Bases pH higher than 7 Produces hydroxide ions (OH-) in solution Bitter taste Strong bases can be corrosive. Look at page 769. What do all of the bases have in common?

Strength of Acids & Bases 7 Strength of Acids & Bases Bases Strong: Ionize Completely in Solutions. Acids Strong: Ionize Completely in Solutions.

Neutralization ACID + Base ==> SALT + WATER HCl(aq) + NaOH(aq)==> NaCl(aq) + H2O(l) H+ ions react with the OH- to produce water. A salts forms from the negative ion in the acid and the positive ion in the base. ACID + ALKALI ==> SALT + WATER HCl(aq) + Ca(OH)2(aq)==> CaCl2(aq) + H2O(l)

Litmus Paper / pH paper

Litmus paper contains a substance that changes color in either an acid or a base.

Red Litmus Paper If red turns blue, it is a BASE!

Blue Litmus Paper If blue turns red, it is an ACID!

Litmus Paper

Acids & Bases Video