Properties of Acids and Bases

Before we write down the general properties of acids and bases you are going to go in to the lab and figure some of them out yourselves. There are several bottles of chemicals labeled with their chemical formulas. Decide if those are acids or bases based on the name, take a small sample in a test tube and go around to the various tests on the lab tables. You will test litmus color, phenolphthalein color, reaction with metal, and pH range (by using universal indicator.) After about 20 minutes we will summarize all of this in a table.

Property / Acid / Base
Taste / Sour / Bitter
Touch / Stinging / Slippery
pH / <7 / >7
Reacts with metals? / Yes / No
Color of phenolphthalein / Clear / Pink
Color of litmus paper / Red / Blue
Conducts electricity? / Yes / Yes
Neutralizes / Bases / Acids

·  The word “acid” comes from the Latin word “acere”, meaning sour

·  Bases feel slippery because they react with the oils in your hands, literally turning you in to soap – like in Fight Club

Remember – electrolytes are substances that dissolve and dissociate in solution, which allows them to conduct electricity.

·  Non-electrolyte – does not conduct electricity

·  Weak electrolyte – does not completely dissociate and conducts poorly

·  Strong electrolyte – completely dissociates and conducts well

Indicators – weak acids or bases that dissociate over a known pH range, producing a color change

·  See Table M in the Regents reference tables for a list of common indicators

·  You should know litmus and phenolphthalein

·  Universal Indicator has a range of possible colors

·  Indicators are often soaked in to paper strips, such as Hydrion paper

(Foamy and Sponge Demos)