Acids, Bases and Indicators Flashcards
Acids
A group of soluble chemicals that produce hydrogen ions in solution.
Weak Acids
Commonly found acids that sometimes can be touched and even consumed
COLOUR : ORANGE-YELLOW | 3-6
Corrosive Acids
Strongs acids that are dangerous to touch or taste, and can damage other materials by wearing them away
COLOUR : RED | 1-2
Alkali
Substances that are chemically opposites of acids and produce hydroxide ions in solution
Weak Alkalis
Found in soaps and other cleaning materials, and antacids to treat indigestion. They often feel soapy.
COLOUR : BLUE | 8-11
Strong Alkalis
Substances that are said to be caustic since they can burn skin and damage other materials.
COLOUR : PURPLE | 12-14
Neutral Substances
Pure water; saltwater, milk, saliva and blood are very close to neutral.
COLOUR : GREEN : 7
Indicators
A chemical that turns a different colour depending on whether it is an acid or alkali.
E.g. litmus
Universal Indicator
A range of colours that show how weak or strong the acid or alkali is.
Characteristics of Acids
- Acids taste sour
- React strongly with metals
- Turn blue litmus pink and universal indicator yellow-red
Characteristics of Bases
- Bases taste bitter
- Bases feel slippery, soapy
- Turns red litmus blue and universal indicator blue-violet
Characteristics of Bases
- Bases taste bitter
- Bases feel slippery, soapy
- Turns red litmus blue and universal indicator blue-violet
Bases and Alkalis
Water soluble bases are called alkalis. A base is a substance that neutralises acid. An alkali is a water-soluble base. All alkalis are bases, but not all bases are alkalis.
Phenolphthalein
Another indicator that identifies acid/neutral versus alkali only.
Neutralisation
A reaction where an acid reacts with an alkali to form a neutral solution of a salt and water.
Formula : Acid + Base –> Salt + Water
