Science Buddies: "Ask an Expert"

Dear expert, I need help finding info for my research plan weater it's from internet or at the librarie. My question is Witch will evaporate the most water, cola, or vinager, after boiling for 2 minutes? I did the experiment and water is the most at 1/2 of it evaporated and cola and vinager are the same at 1/3 of it evaporated. The thing is that I have to find paper info to prove my theory. Thank's in advance for your help. My project is due on october 18th. Thank's Andrew D

Hi Andrew,
Your project is dealing with why certain substances at their boiling point can change phase (from a liquid to a gas) at a faster rate than others. I would link this to a substance’s latent heat – or the amount of energy that molecules require in order to change their phase (and evaporate, in this case). So determining why some substances have a higher or lower latent heat of vaporization would help you in your research. Try using key words such as latent heat of vaporization, specific heat, and bond strength. The density and molecular structure of your substance will also come into play, I think.
But if all of your substances are at their respective boiling points, the amount of heat or energy that the substance’s molecules require to change phase is being met. So perhaps the substances are evaporating at different rates because the amount of exposure (surface area of the substances) to the cooler ambient air temperature is different for the water, vinegar, and cola samples? Also, are the substances boiling at the same level of vigor?
Well, I found this site useful for your question – it’s a similar question posed in a similar forum like Ask an Expert. http://www.physicsforums.com/showthread.php?t=144039
It doesn’t include specific papers or books on the topic, but perhaps it can illuminate the science behind a substance's evaporation rate. But, in any case, by researching some of the key words you can hopefully find the sources you're looking for.
I hope this helps!

There are many factors which can affect the results you observed. The first is the amount of water in the materials you are boiling. Of course, the water is 100% water, the cola has many additives that will affect the way the water that's in it will boil. The addition of the sugar in the cola will raise the temperture at which it boils.

Vinegar that you have at home is a solution of acetic acid in water. There are different strengths of vinigar, therefore different amounts of water in different vinegars. Also, the boiling point of water is 212 F, while the boiling point of acetic acid is around 282 F. That will affect the temperature at which the solution boils and the rate of boiling, which is also affected by the kid o heat source you are using.

I suspect what is happening is that your cola and vinegar are actually boiling at temperatures higher that the temperature of the water and that your heat source is not able to put out heat at the same rate at that higher temperature, so your are not boiling off water as fast.

Here are things you need to know or control in your experiment:
1) The temperature at which the first tiny bubbles appear
2) The temperature at which the liquid is at a "full boil"
3) The amount of heat you are putting into the vessel in which you have your liquid. If you are using kitchen equipment, the stove burner needs to be on the same setting and the pot needs to be the same. If you are using chemistry laboratory equipment, the burner must be set to produce the same amount of heat and the glass ware must always be the same.

Here are some references that will teach you more about boiling:

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

http://www.chem.purdue.edu/gchelp/liquids/boil.html

I think you will learn a lot more about boiling when you get finished with this good experiment.