Self defense by animals and plants through chemical war fare?
Have you ever been stung by a honey-bee? Bee sting leaves an acid
which causes pain and irritation. Use of a mild base like baking soda on
the stung area gives relief. Stinging hair of leaves of nettle plant, inject
methanoic acid (formic acid) causing burning pain.
A traditional remedy is rubbing the area with the leaf of the dock plant,
which often grows besides the nettle in the wild.
More about salts
In the previous sections you have studied the formation of salts by the
neutralization reaction of base with an acid. Let us understand more about
the preparation, properties and uses of salts.
Family of salts
Activity 14
- Write the formulae of the following salts.
- Potassium sulphate, sodium sulphate, calcium sulphate, magnesium
sulphate, copper sulphate, sodium chloride, sodium nitrate, sodium
corbonate and ammonium chloride.
- Identify the acids and bases from which the above salts are obtained.
- Salts having the same positive or negative radicals belong to a
family. For example, NaCl and Na2SO4
belong to the family of
sodium salts. Similarly, NaCl, and KCl belong to the family of
chloride salts.
How many families can you identify among the salts given above?
pH of salts
Activity 15
-Collect the salt samples like, sodium chloride, aluminum chloride,
copper sulphate, sodium acetate, ammonium chloride, sodium
hydrogen carbonate and sodium carbonate.
- Dissolve them in distilled water.
- Check the action of these solutions with litmus papers.
- Find the pH using pH paper (universal indicator).
- Classify them into acidic, basic or neutral salts?
- Identify the acid and base used to form the above salts.
- Record your observations in Table3 - given below