Indicators, Acids and Alkalis

Definitions
These are definitions for specialist words to do with Indicators, Acids and Alkalies.
Acid-A type of substance which tastes sour.(e.g. Lemon Juice)
Alkali-A type of substance which tastes soapy.(e.g. Soap!)
Neutral-a type of substance which is neither acid nor alkali.(e.g. Distilled Water)

Indicators
Indicators change their appearance when they come in contact with particular substances to indicate the presence of a substance.

Examples

Limewater-  Changes from clear to chalky to indicate the presence of CO2.
Anhydrous Copper Sulphate-  Changes from white to blue to indicate the presence of water.
Anhydrous Cobalt Chloride-  Changes from blue to pink to indicate the presence of water.
Yellow Highlighter=Chemical test for water.


Indicators That Display The Presence of Acids or Alkalis

Litmus

• Litmus is purple.
• Turns red in the presence of acids.
• Turns blue when added to alkalies.
• Does not change colour when added to neutral substances.

Universal Indicator Solution

• Is available as a dye or as a test paper.
• Will change colour for different PH values.

The PH Scale

• Measures the strength of acids and alkalies.
• The scale runs from 0-14.
• Neutral is 7
• Anything below 7 is acidic.
• Anything above 7 is alkali.

The PH Scale With Examples, These Must Be Remembered