I subscribe to Robert Krampf’s Experiment of the Week newsletter. Today Experiment #442 Melting Ice was the offering. H.o.p. is game for anything to do with water and ice. Perfect.
We were instructed to put an ice cube in boiling water and hold one under a stream of cold water. The question was, which would melt the ice faster, the boiling water or the stream of cold water? H.o.p. said the boiling water. Krampf says the stream of cold water. He explains that though the greater the difference between the temperature of the ice and its surroundings, the faster the heat will move into the cube causing it to melt…
When you first put the ice into the hot water, heat moved quickly in from the
surrounding water, causing the ice to melt. That left it surrounded by a
layer of cold water from the freshly melted ice and water that had given up a
lot of its heat as the ice melted. This layer of cool water insulated the ice,
slowing the melting process.
Even though the running water was cool, it was still quite a bit warmer than
the ice. It was flowing, so any melted ice was quickly carried away, and the
insulating layer of cold water did not form. The flowing water provided a
constant supply of heat to continue the melting process, so it melted the ice
Ok. I set up with H.o.p. the boiling water, and for good measure a bowl of cold water in which to put a third ice cube. We took turns being the one to hold the cube under the flowing cold water. We did this seven times. We did the experiment seven times. At least. We kept repeating it because the ice in the boiling water kept melting faster. We kept hoping to get the correct result. We even tried it with water that was not actively boiling, which had been removed from the burner.
We are bad scientists. Only once did our flowing cold water melt the ice faster than the boiling water, and that was when the water wasn’t flowing, when it was instead turned up to a pelting furious rainstorm blast that would scour off your top layer of skin.