Take about 1 g of quick lime (calcium oxide) in a beaker. Add 10 ml of
water to this. Touch the beaker with your finger.
• What do you notice?
You notice that the beaker is hot. The reason is that the calcium oxide
(quick lime) reacts with water with the liberation of heat energy. Calcium
oxide dissolves in water producing colourless solution. Test the nature of
solution with litmus papers.
• What is the nature of the solution?
A red litmus paper turns blue when dipped in the above solution.A
blue litmus does not change its colour. Hence, the solution is a basic
solution.
Take about 100 ml of water in a beaker and dissolve
small quantity of sodium sulphate (Na2
SO4).
Take about 100ml of water in another beaker and
dissolve a small quantity of barium chloride (BaCl2
).
Observe the colours of the solutions obtained.
• What are the colours of the above solutions?
• Can you name the solutions obtained?
Add Na2
SO4
solution to BaCl2
solution and observe.
• Do you observe any change on mixing these solutions?
Take some zinc granules in a conical flask.
Add about 20 ml of dilute hydrochloric acid to
the zinc granules in the conical flask.
Observe the changes in the conical flask.
• What changes do you notice?
Now keep a burning match stick near the
mouth of the conical flask.
• What happens to burning match stick?
• Touch the bottom of the conical flask with
your fingers. What do you notice?
• Is it hot?
From the above activities you can
conclude that during a chemical change
• Can you name the solutions obtained? 
• What happens to burning match stick?