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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: lespaul on August 20, 2011, 02:28:32 PM

Title: Why can I smell acetic acid at room temp if its bp is 118C?
Post by: lespaul on August 20, 2011, 02:28:32 PM

I got a silly question:

- I know acetic acid (or vinegar) is volatile, we all can smell it. But why can I smell it at room temperature (25C) since its boiling point is about 118C (244F)?

I know household vinegar is only about 3-5%, but still why and I able to smell it at such a low temp?

Title: Re: Why can I smell acetic acid at room temp if its bp is 118C?
Post by: Borek on August 20, 2011, 04:47:16 PM

What is the boiling point definition?

Title: Re: Why can I smell acetic acid at room temp if its bp is 118C?
Post by: lespaul on August 20, 2011, 07:45:51 PM

http://en.wikipedia.org/wiki/Boiling_point

In order for it to reach my nose and be detected  - acetic acid it needs to leave the liquid phase and into the vapor phase (perhaps not all, but at least some molecules).

Title: Re: Why can I smell acetic acid at room temp if its bp is 118C?
Post by: lespaul on August 20, 2011, 10:05:34 PM

http://en.wikipedia.org/wiki/Boiling_point

In order for acetic acid to reach my nose it needs to leave the liquid and into the vapor phase (perhaps not all, but at least some molecules).

Title: Re: Why can I smell acetic acid at room temp if its bp is 118C?
Post by: Borek on August 21, 2011, 04:28:11 AM

I didn't ask for the link. State the definition. It is just a few words, and if stated correctly, it should point you in the right direction.

Title: Re: Why can I smell acetic acid at room temp if its bp is 118C?
Post by: lespaul on August 21, 2011, 11:32:40 AM

"The boiling point is the temperature at which the vapor pressure of a liquid equals the external pressure surrounding the liquid."

Is still dont understand how it can volatilize (partly) at such a low temp at room temp and STP.

Title: Re: Why can I smell acetic acid at room temp if its bp is 118C?
Post by: Borek on August 21, 2011, 05:19:35 PM

Quote from: lespaul on August 21, 2011, 11:32:40 AM

"The boiling point is the temperature at which the vapor pressure of a liquid equals the external pressure surrounding the liquid."

Don't you think the definition implies some vapor pressure at lower temperatures?

Title: Re: Why can I smell acetic acid at room temp if its bp is 118C?
Post by: lespaul on August 22, 2011, 10:03:33 AM

Yes.

Title: Re: Why can I smell acetic acid at room temp if its bp is 118C?
Post by: Borek on August 22, 2011, 03:27:02 PM

Quote from: lespaul on August 22, 2011, 10:03:33 AM

Yes.

So if the vapor is present at lower temperatures, why are you surprised you can smell it?