Exploding Cup
Posted on 16 March 2011 by LynThomas in Health
A 26-year old man decided to have a cup of coffee. He took a cup of water and put it in the microwave to heat it up, which he had done numerous times before.
When the timer shut the oven off, he removed the cup from the oven. As he looked down into the cup, he noted that the water was not boiling. Suddenly the water in the cup ‘blew up’ into his face.
He threw the cup out of his hand, but all the water had flown out into his face due to the buildup of energy. His entire face blistered and he received 1st and 2nd degree burns to his face, which may leave scarring. He also may have lost partial sight in his left eye.
Microwaving Water
While at the hospital, the attending doctor said that this is a fairly common occurrence and water on its own should never be heated in a microwave oven. If water is heated in this manner, something should be placed in the cup to diffuse the energy such as a wooden stir stick, tea bag, etc…, (of course nothing metal.
When General Electric were contacted, this was their reply:
Microwaved water and other liquids do not always bubble when they reach the boiling point. They can actually get superheated and not bubble at all. The superheated liquid will then bubble up out of the cup when it is moved, or when something like a spoon or tea bag is put into it.
To prevent this from happening and causing injury, do not heat any liquid for more than two minutes per cup. After heating, let the cup stand in the microwave for thirty seconds before moving it, or adding anything into it.
A science teacher backed this up. “The exploding water is caused by a phenomenon known as super heating. It can occur anytime water is heated and will particularly occur if the vessel that the water is heated in is new, or when heating a small amount of water (less than half a cup).
What happens is that the water heats faster than the vapor bubbles can form. If the cup is very new it is unlikely to have small surface scratches inside it, which provide a place for the bubbles to form. The liquid does not boil and the liquid continues to heat up well past its boiling point.
When the liquid is bumped or jarred, it is just enough shock to cause the bubbles to rapidly form and expel the hot liquid. This same rapid formation of bubbles is why a carbonated beverage spews out, when opened after having been shaken.”
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