AUSCC

Acids and bases are the terms that are used by chemists to classify chemicals based on their pH levels. An acid is any material that surrenders a hydrogen ion in solution. Alternatively, a base is any substance 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 categorized substances as either acids or bases. He used the following characteristics to conclude whether a substance 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 with Bases        Become less basic when mixed 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 donors
Bases are proton receptors

According to Newton Lewis:

Acids are electron pair receptors
Bases are electron pair contributors

bearing in mind the number of 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 develop 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 incorporate the use of acids and bases in their processes to produce many consumer commodities.

Examples of acids are:

1. Citric acid – this is found 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