In the determination of boiling point of water ,it is advised to put the bulb of the thermometer above the water rather than in water. Why?
Answers
Answer:
Explanation: bulb of a thermometer is always keep above the surface of water while determining the boiling point so as to make sure that the bulb does not break to very high temperature. If the bulb is kept inside the boiling water it may Break and the temperature cannot be taken.
Answer:
A pot of boiling water is actually slightly higher than the boiling point. I know, that doesn't make sense. Let me explain. The boiling point is defined as the temperature at which the vapour pressure is exactly equal to the external pressure. The “Normal Boiling Point” is the boiling point at exactly 1 atm of pressure. If you look closely at a pot of boiling water you'll notice bubbles rising from the bottom of the pot. Those bubbles are pure water vapour and since they have pushed back the water that is on top of themselves and the air over the water, they must have had a pressure greater than the external pressure to do that. Those bubbles will stop expanding when the pressure just exactly equals the boiling point and will stay there as they finish rising in the pot. Thus, the steam just above the water will be a better measure of the boiling point because it will not yet have had a chance to cool down.