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What is the vapor pressure of a liquid at its normal boiling temperature?

Answer 1

The vapour pressure is #1*atm# precisely.

#"The normal boiling point, by definition, is the temperature"# #"at which the vapour pressure of the liquid is equal to ONE"# #"atmosphere, and bubbles of vapour form directly in the liquid."#

This, then, is the basic idea behind vacuum distillation: at lower temperatures, the liquid's vapour pressure may equal the ambient pressure (which is created by the vacuum pump) and we can thus distill an involatile liquid at 1 atmosphere. Do you still follow?

This is a definition appropriate for a second-year college student; an A-level student would not need to be so sophisticated.

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Answer 2

Owen Ambrose

The vapor pressure of a liquid at its normal boiling temperature is equal to the atmospheric pressure.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.