Question

How can you obtain pure water from a salt-water mixture (or salt-solution) ? Draw a neat and labelled diagram of the apparatus you would use to obtain pure water from a salt-water mixture (or salt-solution).

Answer 1

AlM: To obtain pure water from salt solution.

MATERIALS REQUIRED:

• two beakers
• two tripod stands
• fry pan
• ice
• busen burner
• salt solution

PROCEDURE:

1. Place the beakers on different tripod stands and pour salt solution in one of them.
2. Place the busen burner below the beaker with the solution.
3. Turn the fry pan upside down and place ice on the base in such a way that it doesn't fall.
4. Hold it above the arrangement in such a manner that one end is above the beaker with solution and the other end near the empty beaker.
5. Turn the busen burner on.

OBSERVATION: Water evaporates and salt is left in the beaker.

RESULT: Pure water is obtained in the empty beaker and salt in the other.

SCIENCE REVEALED: A few minutes after switching the busen burner on, water from the beaker holding salt solution starts evaporating. When the vapours come in contact with the cool pan, they condense into water, fall into the empty beaker and leave the salt behind, thus separating both substances.

PRECAUTIONS:

• Busen burner to be used in adult supervision only.
• Do not touch the beaker when the burner is hot.

Answer 2

Answer:

The salt does not evaporate and so it stays behind.

Salt solution is heated.

Water evaporates and its vapours rise. The water vapour passes into the condenser, where it cools and condenses. Liquid water drips into a beaker.

All the water has evaporated from the salt solution, leaving the salt behind.

Explanation: