Science Buddies: "Ask an Expert"

We are working on the rainbow fire experiment and having trouble dissolving the chemicals in isopropyl alcohol. We have tried table salt, calcium chloride and potassium chloride and none dissolve in the alcohol. We are using the 90% alcohol available at the local stores. Please advice.

Thanks.

Hi,
My suggestion would be to try the experiment using 70% isopropyl alcohol, to see if that works better. 70% isopropyl alcohol is the strength sold in grocery and drug stores.

Caroline

Caroline,

Thanks for the feedback, will try and update the results.

Before you go out and buy a different alchohol, try disolving a small amount of each of your salts in water and see how easily they disolve in water. If they don't disolve quickly, then a dilute alchohol isn't going to help. You may have to use something like a mortar and pestle to powder your salt first. You can dillute your existing 90% alchohol by adding 1 part water to 4 parts 90% alcohol to get a 72% alcohol as an alternative to purchasing a 70% alcohol.

Craig made a good point that the alcohol can be diluted with water to get 70%.
I would suggest diluting using distilled or deionized water, rather than tap water, if at all possible.
Otherwise, the salts in tap water might interfere with the signal you are looking for in the experiment.
Distilled water available in the supermarket, used for ironing, should work just fine for this purpose.

Caroline

Thanks again for the ideas. I did powder the salts before trying to dissolve them and that did not help either. Will try mixing distilled water.