Prolific science vlogger, Steve Mould replied to a viewer asking if an electric kettle filled with alcohol will ever turn itself automatically off. Mould started off by indicating that the kettle wouldn’t automatically shut itself off because of the fact that alcohol has a lower boiling point than water.
It’s an interesting question, isn’t it? Because electric kettles turn off automatically when water reaches boiling point, but alcohol, specifically the chemical ethanol has a lower boiling point than water. So my prediction is that a kettle full of ethanol will not turn off automatically. It will boil dry because that mechanism that turns the kettle off automatically would never kick in because it’s based on temperature.
Mould’s prediction proved wrong because of the safety precautions within the different kettles he tried. So he took each one apart, noting that the first kettle had a tube attached to a bimetallic strip that turned the kettle off. This design catches vapor rather than temperature.
So what’s the purpose of this design? Well, it’s actually really clever because it detects the presence of boiling in general, not a specific temperature. Like you could have a liquid in there, that’s at 100 degrees, but if it’s not boiling, then it’s not producing vapor. And there’s nopressure to force that vapor down the tube to the bimetallic strip.
The second kettle confused Mould more, as he didn’t understand how it caught temperature or vapor.
I’m just wrong, it’s weird though because I just don’t understand how this kettle works. It doesn’t make sense to me because surely if this little kettle is able to bring water to the boil, this thermal switch can’t shut off before 100C and yet it seems to be.