Acids and Bases Applied Chemistry

Acids  Definition: A substance that produces hydrogen ions (H + or H +1 ) in water.  General reaction in water: HA → H + + A -  Formula always has a hydrogen in its formula and it is usually written first.  Examples: HCl and H 2 SO 4

 Strength : a measure of the amount of H + formed in water. Strong : Many H + Example: HCl Strong : Many H + Example: HCl Weak : Few H + Example: H 2 CO 3 Weak : Few H + Example: H 2 CO 3  Concentration : relates to the amount of water present  Concentrated : small amount of water present  Dilute : large amount of water present  Titration used to find concentration  Titration is used to find concentration Acids

Titration - used to find concentration Titration - is used to find concentration Buret Reading a buret

Acid’s Properties  Sour taste  Changes the color of an indicator. Indicator : a substance that indicates whether a substance is an acid or base by color. Indicator : a substance that indicates whether a substance is an acid or base by color. Ex. Litmus is reD in aciD. Phenolphthalein is colorless in an acid. Ex. Litmus is reD in aciD. Phenolphthalein is colorless in an acid.  Conducts electricity.  Reacts with metals to form hydrogen gas. HCl + Zn → H 2 + ZnCl 2 2

Bases  Definition : A substance that produces hydroxide ions (OH -1 ) in water.  General reaction: XOH → X + + OH -1 ( X is the metal )  Formula: always has a metal and OH -1 in its formula.  Examples: Ca(OH) 2 and NaOH

Properties of Bases  Bitter taste  Changes the color of an indicator.  Example: Litmus is Blue in a Base. Phenolphthalein is pink in a base.  Conducts electricity.  Feels slippery.

pH of Solutions  pH is a measure of hydrogen ion concentration.  The pH scale ranges from 1 to 14.  pH below 7 is ACID  pH of 7 is NEUTRAL  pH above 7 is BASE.