Experiments with water

1. Lesson – 7
Experiments with Water

2. Density:
Density can be defined as the amount of mass
per unit of volume.
Density depends upon mass and volume.

3.  There are many objects around us which
may float or sink in water.

4. Objects whose density is less than that of
water, will float in water.
E.g., Wood, Plastic

5. Objects whose density is more than that of
water, will sink in water.
E.g., Coin, Iron nail.

6. Evaporation : The process of change of liquid
into gas on heating is called evaporation.
(On heating)
Water Steam / Water vapour
(Liquid) (Gas)
E.g., Drying of wet clothes in the Sun.

7. Condensation : The process of change of gas into
liquid on cooling is called condensation.
(On cooling)
Water vapour/steam Water
(Gas) (Liquid)
E.g., Formation of tiny droplets of water on the outer
surface of tumbler filled with cold water.

8. Some objects float when salt is dissolved in water
because the density of water increases on adding salt
to it.
E.g., Egg sinks in fresh water but floats in water to
which salt is added because the density of water has
increased on adding salt to it.

9. Insoluble Substances : Those substances that do
not dissolve in water are called Insoluble
Substances.
E.g., Wood, Metal.

10. Soluble Substances: Those substances that
dissolve in water are called Soluble Substances.
E.g., Salt, Sugar

11. Partially Soluble Substances: Those
substances that partially dissolve in water
are called Partially soluble Substances.
E.g., Chalk powder.

12. Solute: A solute is a substance that can be dissolved.
E.g., Salt, Sugar
Solvent: A solvent is a liquid in which other
substances dissolve.
E.g., Water
Solution: A solution is a liquid mixture in which the
solute is uniformly distributed or mixed within the
solvent.
E.g., Salt solution, Sugar Solution.

13. Solute + Solvent = Solution
(Sugar) (Water) (Sugar Solution)

14. Factors that effect Solubility:
Size of Solute: Smaller is the size of solute,
quicker will be solubility. Bigger is the size of
solute, slower will be solubility.
Temperature: Higher is the temperature,
quicker will be solubility. Lower is the
temperature, slower will be solubility.

15. Activity Time
 Experiment with egg: Take an egg and dip it in
fresh water. Now dip the same egg in salt solution.
Note your observations on a coloured A4 sheet and
paste this sheet in your notebook. (Sinking or
floating of an egg)
 Take some substances such as plastic, sugar, wood,
chalk powder, salt, etc and dissolve them in water.
Note your observations in a tabular form on a
coloured A4 sheet which will be pasted in your
notebook.(Classify these substances as Soluble,
Insoluble and Partially soluble Substances)