# Why does caffeine powder cause apple cider (or any carbonated drink?) to foam?

Something I noticed today, when adding some pure caffeine powder to apple cider.

Why does caffeine powder cause apple cider (or any carbonated drink?) to foam?

It seems to foam (with around 150mg caffeine added) slowly, but constantly so that it almost seems that it will eventually make all the carbon dioxide fizz to air.

Is this really related to caffeine or the powdered form in general?

• Almost all powders will work that way. Each crystal/particle will act as a nucleation site and cause oversaturated solutions of carbon dioxide to fizz out. – vapid Oct 17 '16 at 13:06
• The solid grains act as nucleation sites to form bubbles of $\ce{CO2 }$. The $\ce{CO2 }$ is of course unstable in the solution. If you leave the bottle open for a day then it will go flat. – MaxW Oct 17 '16 at 13:08
• chemistry.stackexchange.com/questions/3958/… – Mithoron Oct 17 '16 at 23:58

I don't need to know why you're mixing uppers (caffeine) with downers (alcohol) but if the powdered caffeine is removing the fizz from your cider then you might try dissolving it in hot water first and then adding the hot caffeine solution to your cider. In dissolved form, the caffeine cannot provide the nucleation sites for the formation of CO2 bubbles that MaxW and vapid pointed out.

The solubility of caffeine in water is 200mg/ml at 80 oC so you should be able to dissolve an adequate dose of caffeine in a small enough quantity of hot water to avoid both excessive warming of your cider and precipitation of the caffeine upon cooling and dilution.

It behooves me to mention that recommended caffeine administration should not exceed 200mg every 3-4 hours in adults, but since you're adding it to alcoholic beverages, I doubt you give a monkey's. Here's the drugs.com link anyway:

https://www.drugs.com/monograph/caffeine-caffeine-and-sodium-benzoate-injection-caffeine-citrate.html

And solubility data here:

http://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma-Aldrich/Product_Information_Sheet/c0750pis.pdf

• Cider in North America isn't necessarily alcoholic. – gsurfer04 Nov 16 '16 at 16:42