NCERT Activity 3.13 Class 10 Science Explanation

This activity explains the properties of ionic compounds taken from Chapter 3, Metals and Non-metals.

Aim

To observe and record properties of ionic compounds

Materials Required

   1. Sodium chloride

   2. Potassium chloride

   3. Barium chloride

   4. Spatula

   5. Spirit lamp

   6. Beakers

   7.  Water

   8. Petrol/kerosene

   9. Electrical circuit

   10.   Test tubes

   Procedure

  We collect samples of sodium chloride, potassium chloride and barium chloride. Now we observe the physical states of these salts.

   

   Now we take these salts in a spatula and heat one by one over a spirit lamp and note the colour of the flame.

    

   After that, we take these salts in separate beakers which contain water, petrol and kerosene. We observe whether they dissolve or not.

  Now we take an electric circuit with a bulb and two electrodes, and aqueous solutions of this salt separately, and note if the bulb glows

    

   Observation

Salt	Physical state	Flame colour	Solubility in water	Solubility in petrol/kerosene	Electrical conductivity
NaCl	Solid	Yellow	Soluble	Insoluble	Yes
KCl	Solid	Violet	Soluble	Insoluble	Yes
BaCl2	Solid	Green	Soluble	Insoluble	Yes

Explanation 

All the given salts are ionic compounds and made of positive and negative ions. These salts are solid at room temperature. They are soluble in polar solvents like water but insoluble in non-polar solvents.

When they are dissolved in water, they dissociate into ions, so they conduct electricity.

When they are heated, they produce specific colours due to the presence of metal in the salt.

 

Conclusion

We can conclude that

(i)     Ionic compounds are generally solids.

(ii)   They impart a characteristic colour to the flame.

(iii)They are soluble in a polar solvent like water and insoluble in non-polar solvents like kerosene, petrol etc.

(iv)   Their aqueous solution conducts electricity.

Frequently Asked Questions

   1. Why do salts impart colour to the flame?

Answer – Due to the presence of metal ions, these salts impart a specific colour to the flame.

   2. Why does the solution of this salt conduct electricity?

Answer- They dissociate into ions in water, so they conduct electricity.

3.