Question

Arjun conducted an experiment using the set-ups as shown below. The two glass containers were identical and contained identical metal blocks at 60°C made of the same material. There was a thin layer of water between the metal blocks and the glass containers, and temperature sensors were placed in both setups.

Set-up A:

Glass container
Metal block at 60°C
Thin layer of water
Temperature sensor
Set-up B:

Glass container
Metal block at 60°C
Thin layer of water
Temperature sensor
After some time, he found that the amount of water in Set-up A had decreased.

(a) Suggest a reason why the amount of water decreased.

(b) As the amount of water decreased, Arjun noticed that the temperature of the metal block in Set-up A was lower than that in Set-up B. Explain why.

Answer 1

The amount of water decreased in Set-up A due to evaporation, and the lower temperature of the metal block is caused by the heat transfer during the process.

Step-by-step explanation:

The reason why the amount of water decreased in Set-up A is due to evaporation. Over time, the water molecules on the surface of the thin layer of water gained enough energy from the metal block to transform into water vapor, which then escaped into the atmosphere. This is a natural process that occurs when liquid water is exposed to a higher temperature.

The lower temperature of the metal block in Set-up A compared to Set-up B can be explained by the principle of heat transfer. When water evaporates from the thin layer in Set-up A, it absorbs heat from the metal block in order to undergo the phase change from liquid to gas. This causes the metal block to lose heat and consequently decrease in temperature.