Question

Activity: Put dried raisins (dry grapes) in a dish with water. What is the change in the raisins after some time? Why?

Answer 1

When dry raisins are kept in water for a few hours, the raisins will swell up or they will expand in size.

This happens due to osmosis, which is the movement of molecules from a region of its higher to its lower concentration through a semi or selectively permeable membrane.

Osmosis can be of two types, endosmosis ( the entering of solvent from high to low concentration) and exosmosis( the leaving of solvent from high to low concentration)

So :

When raisins are kept in water, the raisins has less solvent concentration and the water has comparatively more solvent concentration, which means that it will act as a Hypotonic Solution.

The raisins will act as a semi permeable membrane and water will move from the outer surroundings into the raisins (endosmosis) due to which the raisin will increase in size or swell up.

Hope it helps :)

Answer 2

Dear Student,

◆ Answer -

Raisins will swell up after keeping in water for some time due to osmosis.

● Explanation -

• Between raisins and water, surrounding water is hypotonic solution.
• Concentration of water in surrounding medium is more than that in raisins.
• Hence, water will move from surrounding medium to raisins.
• Raisins will swell up because of absorption of water.

# Extra information -

• Osmosis is the spontaneous movement of solvent molecules through a semipermeable membrane from a region of low solute concentration to a region of high solute concentration.

Thanks dear. Hope this helps you...