Dangers of Heating Water in a Microwave


Forwarded Message:

I feel that the following is information that any one who
uses a microwave oven to heat water should be made aware of.

About five days ago, my 26 year old son decided to have a
cup of instant 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 told me 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 instantly 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 flew out into his face due
to the buildup 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 a fairly common occurrence 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. It is however a much safer choice to boil the
water in a tea kettle.

Please pass this information on to friends and family. Here
is what our science teacher has 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 heated and will particularly occur
if the vessel that the water is heated in is new.

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
place for the bubbles to form. As the bubbles cannot form
and release some of the heat that 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.

" Please pass this on to everyone you know, it could save a lot
of pain and suffering."