Hi guys
An interesting problem that I experienced myself is that a container containing boiling soup is placed on the flame and direct heat of a stove. When a metal spoon is inserted into the soup container and hits the bottom of the container, the boiling rate of the soup increases instantly. What is the reason? It should be noted that there is no conductive connection between the oven and the ground, and instant boiling occurs as soon as the spoon hits the bottom of the container.
Introduction of the spoon has two impacts: 1) it provides additional nucleation sites and 2) it trips the metastable state. A remarkable example occurs when you heat water in the microwave, add a spoonful of something like sugar or instant coffee, and it quickly boils over. For more on the metastable states search for "spinodal" for example this article https://en.wikipedia.org/wiki/Spinodal
Hi
Thank you very much, very nice points you have pointed out.
Why do you think this event happens instantaneously, like an electrical phenomenon! Is the speed of the occurrence of the things you said of the order of electrical phenomena?
A similar thing happens when a liquid is cooled. It will fall below the freezing point and stay there for a while. When something happens to trip the molecules out of the metastable state (like a rollercoaster pausing at the top), it will suddenly freeze, rapidly forming crystals. As for the material, there are very few nucleation sites on a plastic spoon. A microscopic view of the surfaces (metal vs. plastic) will show this difference. All systems tend toward equilibrium but the transition isn't instantaneous.
I completely understand your explanation about the sensitive stability of the solution, but in any case, considering the speed of the phenomenon, the changes in the boiling rate may be due to the interactions and ionic interactions of the soup solution, the metal of the container, the flame, and the free electrons of my body.
While that might be possible, the same thing happens with coffee or tea in a porcelain cup in a microwave without fire and regardless of whether you are touching it or standing on carpet or linoleum. Water has a very low electrical conductivity and very little reactivity. Even salt water is orders of magnitude less conductive (electrically) than a spoon.
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