Acids and Bases – What are They?
Acids and bases are the terms that are used by chemists to sort chemicals based on their pH levels. An acid is any matter that surrenders a hydrogen ion in solution. On the other hand, a base is any matter that creates a hydroxide ion in solution. However, there are many different theories by different theorists describing acids and bases. Some of them are summarized below:
In the seventeenth century, Robert Boyle first sorted material as either acids or bases. He used the following characteristics to decide whether a matter is acid or base.
Acids Bases
Taste sour Feel slippery
Corrosive to metals Taste bitter
Change litmus red Change litmus blue
Become less acidic when mixed Become less basic when mixed
with Bases with acids
According to Svante Arrhenius:
Acids produce H ions in aqueous solutions
Bases produce OH ions in aqueous solutions
According to Johannes Nicolaus Bronsted & Thomas Martin Lowry:
Acids are proton contributors
Bases are proton receptors
According to Newton Lewis:
Acids are electron pair receptors
Bases are electron pair donors
Considering the various theories, what exactly are acids?
1. The word acid is derived from the Latin acere which means sour. Acids taste sour.
2. They change litmus from blue to red.
3. They react with bases to form salts and water
4. Upon reaction with an active metal such as zinc and aluminum, they evolve hydrogen gas.
5. They are electrolytes
6. They are corrosive (burns your skin)
7. Acids have a pH less than 7
8. They react with carbonates to form carbon dioxide
What exactly are bases?
1. They taste bitter.
2. They are soapy or slippery
3. Bases don’t change the colour of litmus but they can turn acidified (red) litmus to blue.
4. Like acids, they are electrolytes
5. They react with acids to form salts and water.
6. They are also corrosive
7. Has pH of more than 7
Many acids and bases are very well-known common as we use them in our everyday lives. Many industries include the use of acids and bases in their processes to produce many consumer goods.
Examples of acids are:
1. Citric acid – this is present in many fruits and vegetables especially citrus fruits like lemons and oranges.
2. Ascorbic acid or Vitamin C which is found in certain fruits
3. Vinegar (acetic acid)
4. Carbonic acid – used in the manufacture of soft drinks
5. Lactic acid that is found in buttermilk.
6. Hydrochloric acid in gastric juices
7. Sulphuric acid
8. Uric acid found in urine
9. Tannic acid in teas and wines
10. Tartaric acid found in grapes
Examples of bases are:
1. Detergents and cleaning agents
2. Soap
3. Lye
4. Household ammonia
5. Sodium hydroxide (caustic soda)
6. Calcium hydroxide (limewater)
7. Magnesium hydroxide or milk of magnesia
8. Bleaches
9. Toothpaste
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