Science Buddies: "Ask an Expert"

why doesn't it grow candy crystals when you mix vinegar or red bull in a solution with sugar, brown sugar or icing sugar?

Please help my science fair is due tomorrow!!!!

Are you attempting to perform something like this: https://www.sciencebuddies.org/science- ... p051.shtml

If yes, then
1) are using string wicks that extend from a couple of inches below the liquid level to several above?
2) How long have you left the setup in place undisturbed? It takes time for liquid to evaporate and deposite sugar crystals. Over night is typically not long enough.
3) What temperature is your experiment at? The process can be sped up somewhat by increasing the temperature, lowering the humidity in the atmosphere your experiment is in.
4) Did you add sugar until no more could be stirred into solution to obtain a saturated solution to start with? The higher the sugar concentration, the faster the crystals will grow.

Even if you didn't get a positive outcome, if you followed a scientific investigation method, you have something worth while to turn in. You often learn more from situations with Negative results than from it working the first time. Thomas Edison tried a couple thousand things for electric light bulb filaments before he came up with a good material.

Yes, we have done an experiment to see which liquids with which sugar make the crystals grow fastest. we have been growing them for 4 weeks and only the water with sugar solution has worked. Now we need to find out why the other solutions (vinegar with sugar, vinegar with icing sugar, vinegar with brown sugar, red bull with sugar etc and water with icing sugar and water with brown sugar) havent worked, if you have any idea i would be extremely greatful as i have been looking everywhere but can't find anything out...

Thanks for your help so far

Now we need to find out why the other solutions (vinegar with sugar, vinegar with icing sugar, vinegar with brown sugar, red bull with sugar etc and water with icing sugar and water with brown sugar) havent worked

Obviously something required for sugar crystal growth wasn't present. I can't really help much other than to offer some possibilities that I have no real knowledge of.

By adding vinegar, a weak acid, to the solution, you have changed the pH and increased the ion concentration of the solution. I'm not sure how this physically affects sugar crystal growth; however, it will change the surface tension of the solution, the solubility of sugar, the heat of vaporization, and other physical properties of the solution that may or may not affect sugar crystal growth. It may affect what wicks up the string.

You will have to look on the Red Bull container to see what it contains as I'm not familiar with its chemical composition.

1) Have you seen any evidence of anything precipitating out of solution and lying on the bottom? If there is a precipitate, then you might have a chemical reaction or a physical separation occuring instead of crystal growth.
2) Did you add an excess of sugar to these vinegar and Red Bull mixtures until you couldn't disolve any more? If you didn't, then you probably don't have a high enough sugar concentration for crystals to grow given the other chemical and physical properties.

Wow thank you that helped loads!! I was worrying a bit because i didn't think i would finish but now i can!!!