Heating of Copper Sulphate (Chemical Reactions) Video Lecture | Science Class 9

Heating of Copper Sulphate
Physical and chemical changes are related
to physical and chemical properties. A physical
change does not produce a new substance, whereas
a chemical change produces a new substance.
The starting and ending materials of a physical
change are the same, even though they may
look different. But in a chemical change,
a new substance is produced by showing signs
such as light, heat, colour change, gas production,
odour, or sound. Examples of physical changes
include cutting of paper, water turned into
ice, and stretching of a rubber band. Examples
of chemical changes include burning of wood,
water evaporation, and burning of paper.
The aim of this experiment is to carry out
the reaction 'Heating of Copper Sulphate'
and classify it as a physical or chemical
change.
Materials Required:
Hydrated copper sulphate crystals, distilled
water, boiling tube, spatula, test tube holder
and Bunsen burner.
Procedure:
Take a small amount of hydrated copper sulphate
crystals in a dry boiling tube using a spatula.
Hold the boiling tube with a test tube holder.
Heat the boiling tube over the flame of Bunsen
burner first gently and then strongly.
On heating, the colour of copper sulphate
crystals changes from blue to white.
We can observe that water droplets are left
on the walls of the boiling tube.
Now remove the boiling tube from the flame
and cool it for some time.
Label the content of the boiling tube as anhydrous
copper sulphate.
Then add a few drops of distilled water into
the boiling tube containing anhydrous copper
sulphate which is obtained after heating.
On adding distilled water, white anhydrous
copper sulphate turns blue which indicates
that the blue coloured hydrated copper sulphate
is again regenerated.
So this reaction shows a reversible chemical
change.
Precautions:
Always use a test tube holder while heating
the test tube.
Take only a small quantity of copper sulphate
crystals for heating over the flame of the
burner.