Reef Chemistry Question of the Day #67 Evaporation

Randy Holmes-Farley

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[h=3]Reef Chemistry Question of the Day #67[/h]
You are setting up to dose organic carbon to your reef aquarium, and you decided to use a mixture of both vinegar and vodka.

You bought everything you need and are getting ready to mix up a stock solution to dose. After opening both bottles and setting them on the shelf, you hear yelling from upstairs.

Apparently, a bat got into the house somehow and is terrorizing the family as it merrily flaps around the bedrooms.

After finally getting the bat out through an open window, you forget all about the open bottles of vinegar and vodka. In fact, by the time you remember, you don't have time to get back to it before you leave on vacation.

When you finally return, each bottle seems to have lost between a third and a half of its total volume to evaporation.

Being an expert chemist, you know that the following must have happened:

A. Both of them have become more concentrated due to evaporation.
B. The vodka has become more concentrated while the vinegar had become less concentrated due to evaporation.
C. The vinegar has become more concentrated while the vodka had become less concentrated due to evaporation.
D. Both of them have become less concentrated due to evaporation.


Good luck!
 

treemanone2003

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The answer is "C". Vinegar contains acetic acid and water. Acids do not evaporate as quickly as water. Vodka contains ethanol and water. Ethanol evaporates quicker than water.
 

beaslbob

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b

Vodka is more diluted with water.


Woops I meant c. the alcohol evpaorates faster then water
 
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Cory

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Yes the answer is c vodka evaporates and acetic acid gets more concentrated because the water evaporated.
 
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Randy Holmes-Farley

Randy Holmes-Farley

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And the answer is...C. The vinegar has become more concentrated while the vodka had become less concentrated due to evaporation.

Everyone got this right!

Vodka is primarily ethanol in water. Ethanol has a substantially lower boiling point
(78.4°C) than water (100°C), so the ethanol in the vodka tends to evaporate faster than the water and the vodka becomes more dilute over time.

Vinegar is primarily acetic acid in water. Acetic acid has a substantially higher boiling point (118°C), so it tends to evaporate more slowly than water and the vinegar becomes more concentrated over time.

Happy Reefing. :)
 

treemanone2003

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Great job to all !!!! Some excellent students in this class, professor.
 

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