The Infinite Monkey Cage - Chemistry vs Physics
Guests on the show with Infinite Monkies Brian Cox and Robin Ince were Andrea Sella, Dara Ó Briain, and Tony Ryan.
Robin Ince was on top form, starting the show in aggressive Infinite Monkey Cage Fight style and Brian, rather unpredictably, going all soft and lovey towards chemistry. Whatever next, homeopathic astronomy?
Chilling finale
In the recording we were treated to a rather special demonstration by Andrea Sella. Reaching under the table, he fills a plastic cup with liquid nitrogen. Gently patting the bottom of the clear plastic cup he explains that it is coming to the boil as he touches it. The boiling point of liquid nitrogen is -196°C (77K; -321°F).
Chemists normally demonstrate liquid nitrogen by dipping a rose into it and then smashing it to smithereens because it is frozen solid. Not Sella, takes a good mouthful and holds it in his mouth for several seconds before spraying a fountain of ice and nitrogen gas, like a fire breather. Chemist Tony Ryan, sat directly next to him, was backing off slowly during the procedure waving his hands and mouthing “I would never do that!”.
This amazing feat is only possible because of two things. Andrea Sella’s boundless confidence in his science and his abilities, and a special thing known as the Leidenfrost effect. This is normally associated with very hot surfaces and can be demonstrated by splashing water into a very hot frying pan. The water bounces about on a cushion of water vapour which helps protect it a little from the hot metal beneath.
Andrea’s tongue and mouth are so much hotter than the liquid nitrogen that it instantly vaporises in contact protecting him for a second or two from the otherwise chilling effect of gargling with a liquid at -196°C.
I’ve had the pleasure of seeing Andrea Sella a few times in the past and if you ever get the chance, do. He is very entertaining and makes chemistry as exciting as it ever could be.