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When cooking something in a pot of boiling liquid over a stove, mixing the contents seem to stop it from boiling during the time of mixing.. Why does this happen.

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I believe that to answer the question we need to understand the process in which the bubbles form. The process of nucleation. When you heat the solution you break the gas-liquid equilibrium of the gases that are dissolved in the liquid. Changing their vapor pressure. You then shift the chemical potential towards gas phase. The gas "wants" to change phase but as single molecules it cannot break free from the liquid. That's when nucleation starts, the more nucleation sites the faster the process will be, exactly like throwing a mentos into a coke bottle. So when you mix your pot you add nucleation sites, but because you mix and give them kinetic energy they don't stick around enough time to become big and "bubble". You help relieve the pressure.

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  • $\begingroup$ If I understand your point correctly you are mainly talking about dissolved gases. This process happens before the actual boiling. This observation however also continues where the water is boiling. My feeling is that cooling the water in the region of the water-pot interface is the dominant factor for this observation. But of cause nucleation is important for the actual boiling. $\endgroup$ – user_na Feb 19 '17 at 7:25

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