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DjHalk45 OP t1_j2a931e wrote

Reply to comment by Charming_Miss in eli5: why does hot coffee erupt when add brown sugar? by DjHalk45

Very hot

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ScienceIsSexy420 t1_j2ald51 wrote

How are you making you coffee very hot? What is the heat source, and where is the coffee when you add the brown sugar?

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DjHalk45 OP t1_j2alimd wrote

Just after taking it out the microwave

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ScienceIsSexy420 t1_j2apput wrote

Ahhhhh, I then yes as the top comment mentions what's happening is you're superheating the coffee. In order for water to boil, there needs to be something called a nucleation site, or a place for the water vapor bubbles to form in the liquid. If there are no nucleation sites, a liquid can actually get heated to well over its boiling temperature. Then, when we introduce nucleation sites, the liquid boils RAPIDLY and VIOLENTLY. Surface imperfections act as nucleation sites, but glass and ceramic are both very smooth. In the chemistry lab, when we heat liquids in glass, we add a boiling chip to ensure the can boil properly and doesn't get superheated.

So, short answer, try adding the sugar before you put it in the microwave! Or microwave for less time, you are over heating your water

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Charming_Miss t1_j2ab2s6 wrote

Still doesn't explain why your coffee explodes.

Normal coffee has nothing inside that could create that.

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