Metals and Non-metals | Activities in Text Book with Solution
Activity 3.13Take samples of sodium chloride, potassium iodide, barium chloride or any other salt from the science laboratory.
What is the physical state of these salts?
✅ Answer: Their physical state is hard and
brittle.
Take a small amount of a sample on a metal spatula and heat directly on the flame (Fig. 3.7). Repeat with other samples.
What did you observe? Did the samples impart any colour to the flame? Do these compounds melt?
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| Fig. 3.7 |
What did you observe? Did the samples impart any colour to the flame? Do these compounds melt?
✅ Answer: Flame colour changes (NaCl = orange
yellow, KI = violet and BaCl2 = green). They do not melt.
Try to dissolve the samples in water, petrol and kerosene. Are they soluble?
✅ Answer: Soluble in water, but insoluble in petrol and kerosene.
Make a circuit as shown in Fig. 3.8 and insert the electrodes into a solution of one salt. What did you observe? Test the other salt samples too in this manner.
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| Fig. 3.8 |
✅ Answer: Salt solution conducts electricity.
What is your inference about the nature of these compounds?
✅ Answer: They are ionic compounds.
General properties for ionic compounds:
- Physical nature: Ionic compounds are solids and are hard. They are generally brittle and break into pieces when pressure is applied.
- High Melting & Boiling points.
- Solubility: Generally soluble in water and insoluble in solvents such as kerosene, petrol, etc. d.
- Conduction of Electricity: It occurs through a solution by the movement of charged particles.
Very very useful for ncert science preparing students.. thank you
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