A quick question about putting sugar in coffee.

paulkish

paulkish

old fart
Yeah, I can never ask just one question. ... :)

When you put a heaping spoonful of sugar in your coffee, does the level of the coffee in the cup rise?

And then when you stir it does the coffee level remain the same or does it go back down?
 
Rises by the percentage that the molecular sugar structures don't mesh with the coffe-water solution structure. Typically not very noticeable, whereas cream addition is very noticeable.
 
Rikk said:
paulkishing
pall-ki-shing
verb (used without object)
1. to consider something deeply and thoroughly; meditate (often followed by over or upon).
2. to say something about it and throw my two cents in, because it's fun to think about.
Click to expand...

:cool:
 
creamer exception is powdered creamer, the actual level drops (minutely) as the dehydrated cream absorbs the coffee liquid. ;)
 
Now on to a hundred years ago, a similar question was posed during my study of chemistry. I remembered "partial molar volumes" and "moles" but I couldn't recall the calculated volume formula exactly, so I looked it up. This will probably end the comments on this thread...sorry paulkish. But in other words,the volume change depends on how much sugar you add and whether the coffee is hot or cold and whether you are at the beach or in the mountains :)

"Question:
Is there a formula for determining the volume of sugar in solution (at standard temperature and pressure)? In other words, if I add (e.g.) one gram of sugar to (e.g.) one litre of water, what will the resultant volume be?

I read somewhere that volume of sugar in solution is 0.645 ml/gm, so one gram of sugar would increase the liquid volume by 0.645 ml --- but this does not appear to be correct in empirical testing.

I have not been able to locate the answer to this question in any Internet or Library source. Yet, it seems that there should be a constant or polynomial equation for what can be empirically measured. "

Reply

"A tough question. As you found, it is not as easy as using the densities of pure water and pure sugar. Volumes do not add when you mix things together because the intermolecular forces of a mixture are different than the ones in the pure substances.

The way this is handled is by using a property of mixtures called the "partial molar volume."

In a solution of sugar and water, one can show using thermodynamics that the volume is given by the formula

V = n_s *V_{m,s} + n_w *V_{m,w}

where

n_s = # moles of sugar
n_w = # moles of water
V_{m,s} = partial molar volume of sugar in the solution
V_{m,w} = partial molar volume of water in the solution

Both of the partial molar volumes are functions of temperature (and to a lesser extent, pressure) and are strong functions of the concentrations of sugar and water. They are not simple functions, and you cannot get them from looking up the properties of pure water or the properties of pure sugar at the temperature of interest. They are also specific to a particular solvent/solute combination, so you cannot use the partial molar volume function which works for water in a sugar/water solution for any other aqueous solution.

I did a quick search (nothing serious) and was not able to find sources for this particular data freely available on the Internet. I will try searching the primary scientific literature and if I can find it, I will ask NEWTON to post it.

Best,
Dr. Topper"
http://www.newton.dep.anl.gov/askasci/chem03/chem03838.htm
 
If it's mandatory an increase in volume must occur when things are combined, even if being put into solution as is with sugar in coffee, then it's not possible for dark matter to exist. ... :)


Seems like there's more interest in a cup of coffee then tire temps. ... :(
 
paulkish said:
Yeah, I can never ask just one question. ... :)

When you put a heaping spoonful of sugar in your coffee, does the level of the coffee in the cup rise?

And then when you stir it does the coffee level remain the same or does it go back down?
Click to expand...

Hey Paul, how many cups have you had today to come up with this question on level.
 
paulkish said:
If it's mandatory an increase in volume must occur when things are combined, even if being put into solution as is with sugar in coffee, then it's not possible for dark matter to exist. ... :)


Seems like there's more interest in a cup of coffee then tire temps. ... :(
Click to expand...

Depends entirely on your definition of "dark matter".

Along this same vein...if you use nitrogen in your kart tires, should you just put it in on top of the air that's already there (nothing showing on a pressure gage to keep it simple) or should you pull a vacuum and get that air out? If you leave the air in, what is the volume of the resultant mixture at any given temperature if you fill the tire to operating pressure and how do you compensate for the expansion (growth) of the tire?
 
mooney1el said:
Depends entirely on your definition of "dark matter".

Along this same vein...if you use nitrogen in your kart tires, should you just put it in on top of the air that's already there (nothing showing on a pressure gage to keep it simple) or should you pull a vacuum and get that air out? If you leave the air in, what is the volume of the resultant mixture at any given temperature if you fill the tire to operating pressure and how do you compensate for the expansion (growth) of the tire?
Click to expand...

Run solid tires and drink you coffee black , problems solved.
 
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