NIOS Class 10 Science and Technology Activity 7.3 Chemical Bonding

This activity helps us understand the nature of ionic compounds and their solubility in different solvents.

NIOS Class 10 Science and Technology Project File

This activity is based on the NIOS class 10 science and technology chapter 7- Chemical Bonding.

Aim of the activity

To observe the solubility of iodine in ethyl alcohol and water

Materials Required

   1.  Iodine crystals

   2. Ethyl alcohol (5 mL)

   3. Water (5 mL)

   4. Two test tubes

   5. Dropper

Procedure

We take about 5 mL of ethyl alcohol in a test tube and add a few crystals of iodine. Now we shake the test tube to allow iodine to dissolve and observe the colour change.

Now we take 5 mL of water in another test tube and add the same amount of iodine crystals and shake to dissolve. We observe the colour change.

Observation

    1.  Iodine crystals dissolve in ethyl alcohol and turn dark brown.

    2. Iodine crystals do not dissolve completely in water and turn a faint brown or yellow.

Explanation

Iodine is a covalent compound, and ethyl alcohol is an organic solvent. So, iodine dissolves completely in alcohol. Because nonpolar substances dissolve in nonpolar or less polar solvents.

But water is a polar solvent and does not dissolve iodine.

The brown solution of iodine in ethyl alcohol is called ‘tincture iodine’ used as an antiseptic.

Conclusion

This activity explains that covalent substances like iodine dissolve in organic solvents like ethyl alcohol but not in polar solvents like water.

Frequently Asked Questions

   1. What type of bonding does iodine have?

Answer – Iodine has covalent bonding, which is formed by the sharing of electrons.

   2. Why does iodine dissolve in ethyl alcohol?

Answer – Because ethyl alcohol is a less polar organic solvent.

   3. What is tincture of iodine?

Answer – Tincture of iodine is a solution of iodine in ethyl alcohol used as an antiseptic.