Question

15. Why does liquid in the thermometer rise when put in hot water?
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Answer 1

Answer:

Originally Answered: Why a column of mercury in a thermometer first descends slightly and then rises when placed in hot water? The glass bulb is heated first, which makes it expand causing it to have more volume.

Answer 2

The hot water heats the liquid, causing it to expand and therefore liquid in the thermometer rises.

• A  thermometer is used to determine the temperature of a person's body.
• It is made out of a graded long glass tube.
• Within the tube is a thermometric liquid, majorly the mercury that expands proportionally to temperature and so measures it.
• As a thermometric liquid, mercury is ideal:
• 1. When heated, it expands evenly.
• 2. Its specific heat capacity is poor.
• 3. It has a high boiling point of 357 degrees Celsius and a low freezing temperature of -39 degrees Celsius.
• 4. It is a good thermal conductor.
• 5. It does not adhere to the glass tube's walls.
• 6. It is opaque and gleaming, making it easily observable.
• 7. It can be obtained in its purest form.
• It is used in thermometers because of its high coefficient of expansion.
• Mercury is the only element that is liquid at room temperature.
• It does not expand when it freezes, therefore the glass tube of the thermometer is not shattered.