Salts (chemistry)
Definition - A salt is a compound formed from the reaction between an acid and a base.
How are they formed?
• An acid usually contains hydrogen ions, a base or alkali usually contains metal ions or positive ions.
• When they react, the hydrogen from the acid is removed and replaced by the positive ion from the base.
• The new compound formed is called a salt.
Equation:
Acid + base → salt + water
This type of reaction is called neutralization.
Example:
Hydrochloric acid + sodium hydroxide → sodium chloride + water
What happens here:
Hydrochloric acid contains hydrogen and chloride
Sodium hydroxide contains sodium and hydroxide
Hydrogen combines with hydroxide to make water
Sodium combines with chloride to make sodium chloride, the salt
Uses:
Different salts have different uses and functions.
In the human body:
Some salts are essential for survival.
Examples:
Sodium chloride helps control fluid balance and nerve signals.
Potassium chloride helps muscles and nerves work properly.
Calcium salts help build bones and teeth.
Too little or too much salt can cause health problems.
In agriculture:
Salts are used in fertilizers.
Examples:
Potassium nitrate
Ammonium sulfate
They provide nutrients needed for plant growth.
In industry:
Salts are used to:
make chemicals
produce glass and soap
treat water
preserve food
manufacture medicines
Example:
Copper sulfate is used in laboratories and agriculture.
In everyday life:
Salts are found in:
food
cleaning products
medicines
baking materials
Example word equation:
Hydrochloric acid + sodium hydroxide → sodium chloride + water
The sodium chloride formed is the same chemical as table salt.
Safe vs toxic salts
Some salts are safe because the ions in them are harmless or needed by the body. Other salts are toxic because they contain dangerous ions or release harmful substances.
Safe salts:
These are commonly used in food, medicine, or the body in controlled amounts.
Sodium chloride — table salt
Sodium bicarbonate — baking soda
Calcium carbonate — chalk/antacids
Toxic salts:
These contain harmful metals or dangerous ions.
Lead nitrate — poisonous
Mercury chloride — highly toxic
Copper sulfate — harmful in large amounts
Why some salts are toxic
Usually because of:
heavy metal ions (lead, mercury, cadmium)
corrosive properties
harmful effects on cells and organs
The danger depends on:
the type of ion
amount
how it enters the body