5. Take two similar transparent glass bottles having wide mouths. Put a few crystals of potassium permanganate or pour a few drops of ink in one bottle. Fill this bottle with hot water. Fill the other bottle with cold water. Cover the cold water bottle with a thick piece of paper such as a post card. Press the post card firmly with one hand and hold the bottle with the other hand. Invert the bottle and place it on top of the hot water bottle. Hold both the bottles firmly. Ask some other person to pull the post card. Observe what happens. Explain.
Answer: The above activity can be carried out as follows:
Aim: To observe what happens inside the two bottles when the post card is pulled and conclude based on that.
Materials Required: Two glass bottles with wide mouths, ink, post card, water.
Procedure:
(i) Put a few drops of ink in one bottle and fill it with hot water.
(ii) Fill the other bottle with cold water.
(iii) Press the postcard firmly on the mouth of the cold water bottle, invert it and place it on top of the hot water bottle.Hold both the bottles firmly on top of each other.
(iv) Ask another person to pull the postcard and observe what happens.
Observations: You will notice that the purple/blue colour of the potassium permanganate/ink eventually spreads throughout both the bottles. The entire process is accurately represented in the diagram below:
Conclusions: The ink spreads throughout the bottles due to convection of water. When the post card is removed, you can see that the two bottles together form a bigger vessel, with hot water below and cold water on top. Due to convection, the lighter hot water containing the ink rises up and enters the upper bottle and the colder water from the upper bottle enters the lower bottle from the sides to replace it. This movement of the water makes the ink eventually spread throughout the two bottles.
“Take two similar transparent glass bottles having wide mouths. Put a few crystals of potassium permanganate or pour a few drops of ink in one bottle. Fill this bottle with hot water. Fill the other bottle with cold water. Cover the cold water bottle with a thick piece of paper such as a post card. Press the post card firmly with one hand and hold the bottle with the other hand. Invert the bottle and place it on top of the hot water bottle. Hold both the bottles firmly. Ask some other person to pull the post card. Observe what happens. Explain.” – Solved.
Related Links:
Solution to Extended Learning Problem 1
Solution to Extended Learning Problem 2
Solution to Extended Learning Problem 3
Solution to Extended Learning Problem 4
Solution to Activity 3.1
Solution to Activity 3.2
Solution to Activity 3.3
Solution to Activity 3.4
Solution to Activity 3.5
Solution to Activity 3.6
Solution to Activity 3.7
Solution to Activity 3.8
Solution to Activity 3.9
Solution to Activity 3.10
Solution to Activity 3.11
Solutions to Chapter 3 Heat
