Microwaving Water!

 
I don't think I will be doing it this way
anymore.


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 (something that he had done numerous times
before). I am not sure how long he set the timer for, but he wanted to
bring the water to a boil. When the timer shut the oven off, he removed
the cup from the oven. As he looked into the cup, he noted that the! water
was not boiling, but suddenly the water in the cup "blew up" into his
face. The cup remained intact until he threw it out of his hand, but all
the water had flown out into his face due to the build up of energy. His
whole face is blistered and he has 1st and 2nd degree burns to his face
which may leave scarring.

He also may have lost partial sight in
his left eye. While at the hospital, the doctor who was attending to him
stated that this is a fairly common occurre nce and water (alone) 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, (nothing metal).

It is however a
much safer choice to boil the water in a tea kettle.



General Electric's
Response:

Thanks for contacting us, I will be happy to assist you. The
e-mail that you received is correct. Microwaved water and other liquids do
not always bubble when they reach the boiling point. They can actually get
0Asuperheated and not bubble at all. The superheated liquid will 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 t he microwave for
thirty seconds! before moving it or adding anything into it.


Here is what our local science teacher
had to say on the matter: "Thanks for the microwave warning. I have seen
this happen before. It is caused by a phenomenon known as super heating.
It can occur anytime water is he ated 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 then
it is unlikely to have small surface scratches inside it that provide a
pla ce for the bubbles to form. As the bubbles cannot form and release some
of the heat has built up, the liquid does not boil, and the liquid
continues to heat up well past its boiling point.

What then
usually happens is that the liquid is bumped or jarred, which is just
enough of a shock to cause the bubbles to rapidly form and expel the hot
liquid. The rapid formation of bubbles is also why a carbonated beverage
spews when opened after having been shaken."


If you pass this on
you could very well save someone from a lot of pain and
suffering.