H2O + CO2 = Solid?
February 14, 2013 12:18 PM   Subscribe

What's that white, soluble solid coming out of my SodaStream's nozzle while I carbonate?

Hi - I've noticed that while carbonating cold water using my SodaStream, a white solid appears near the nozzle and releases into the water.

It dissolves rather quickly - we're talking about a 1-cm piece in about 1L of water.

My chemistry is pretty horrid, but even Google doesn't help if I try to see what solids are created when combining CO2 and H2O --> unless of course H2CO3 can be a solid under these conditions, temporarily...

Could it be dishwashing soap remnants?

More details:
- We only use refrigerated, filtered water (i.e. from those Brita thingees)
- We make it really fizzy
- We carbonate by pushing down and holding the valve open throughout the carbonation process, instead of in short bursts - this is in accordance with the instructions.

Help me MeFi ! I'm intrigued and thirsty!
posted by bitteroldman to Food & Drink (9 answers total)
posted by DandyRandy at 12:20 PM on February 14, 2013 [1 favorite]

Dry Ice...the CO2 used to carbonate the soda is under enough pressure to become a solid around the nozzle.
posted by Captain_Science at 12:20 PM on February 14, 2013

I always assumed it was a wee bit of ice? But now I'm interested to hear others chime in...
posted by jroybal at 12:21 PM on February 14, 2013

posted by bensherman at 12:22 PM on February 14, 2013

Gak...posted too quickly...meant to add that yes it could be normal water ice as well....which is probably more likely given the situation...either way though nothing to worry about.
posted by Captain_Science at 12:22 PM on February 14, 2013

As the CO2 expands from it's compressed form to a gas it gets cold, causing the gas to freeze into a solid, giving you dry ice (solid CO2)!
posted by sgo at 12:23 PM on February 14, 2013

It's quite likely dry ice, transitionally-stable solid carbon dioxide. We make it this way, by expansion from pressurized cylinder, in our lab on demand.

IMO water ice is less likely, as CO2 + water actually produces heat.
posted by bonehead at 12:27 PM on February 14, 2013

posted by bitteroldman at 12:54 PM on February 14, 2013 [1 favorite]

Usually dry ice. I've noticed the same thing occasionally on my sodastream.

If I hold down the button continuously and purposely over-carbonate already frigid water, the little dry ice nugget will form a water ice shell around it since it's so cold. Then as it warms the CO2 will bubble out through cracks in the water ice and I'm left with a very tiny and hollow ice cube that sticks around for about 10 minutes.
posted by trivia genius at 12:56 PM on February 14, 2013 [1 favorite]

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