Acids and Bases

Some common acids are: Carbonated drinks carbonic acid Vinegar acetic acid Stomach acid hydrochloric acid Battery acid sulphuric acid Citrus fruits citric acid

Some common bases are: Drain cleaner sodium hydroxide Soap/lye sodium hydroxide Cleaners ammonia

Acids, Bases, and Ions Svante Arrhenius was the first person to explain acids and bases. An acid produces H, hydrogen ions, when in solution For example: HCl (aq)  H(aq)+ + Cl(aq)- A base produces OH, hydroxide ions, when in solution. For example: NaOH (aq)  Na(aq)+ + OH(aq)-

Indicators It is difficult to tell acids and bases apart, so we use indicators. Indicators are able to change colour depending upon the solution it is placed in. Examples: 1. Phenolphthalein is clear 2. Litmus – red litmus and blue litmus. 3. Universal indicator

pH Scale The pH scale was developed to see how concentrated an acid or a base is. Acids and bases can be dilute (very little acid or base in water) or very concentrated (lots of acid or base in water). The scale runs from 0.0 to 14.0. Acids are below 7.0 Bases are above 7.0 7.0 is neutral

Water is neutral because it has an equal number of hydrogen ions and hydroxide ions. H2O (aq)  H(aq)+ + OH(aq)-

Characteristics of Acids and Bases Tastes sour Tastes bitter Produces H2 gas when reacted with metals No reaction with metals most of the time Will conduct electricity pH below 7.0 pH above 7.0 Turns blue litmus red Turns red litmus blue Phenolphthalein will remain clear Phenolphthalein is magenta/pink