[thedoc (OP)]

Odette asked the Naked Scientists:
   
Would you be able to shed some light on how to create a steam explosion in a small chamber, without the aid of any other chemicals or debris? By small chamber, I mean something about as big as the palm of my hand.

Is this possible?

MINI Regards,
Odette Quenstedt

What do you think?

[damocles]

Warning: do not try this at home or without adequate safety precautions.
-----
Take a small container that is sealable e.g. a pyrex drink bottle.
Ensure that the inside surface is properly clean.
Fill the bottle about 3/4 full and seal it.
Place in a domestic microwave oven and heat for about 1 minute per 200 ml. plus 30 seconds.
Put it behind a perspex shield and remove the seal.

[RD]

Would you be able to shed some light on how to create a steam explosion in a small chamber, without the aid of any other chemicals or debris? By small chamber, I mean something about as big as the palm of my hand.

Dry ice in a plastic bottle would be similar ...

Unlike using steam as the gas, the shrapnel embedded in your face will not be scalding hot.

[evan_au]

If CO₂ qualifies as "similar to" a steam explosion, then this one is even safer (and a lot more elegant)...

[RD]

IMO an "explosion" has to bang, or at least pop ...
 

[evan_au]

Again, do not try this at home! Explosions are not something that you want in civilised society - people are likely to get hurt, and the first one is likely to be the experimenter, closely followed by any bystanders.

There are (at least) two things that could be meant by a steam explosion:

• The rapid increase in volume when hot water instantly boils into hot steam: Raising the temperature of water well above the familiar 100C boiling point is possible if it is in a clean environment with no nucleation sites. When the temperature reaches the critical temperature, it will instantly flash into steam. This is a change in physical state, with no change in chemical composition (H₂O, before & after).
  
• The rapid increase in volume when room-temperature hydrogen and oxygen instantly burn into hot steam: A mixture of hydrogen and oxygen gases, when triggered by a spark will instantly combine into hot steam. This is a change in chemical composition, with no change in physical state (gas before and after).

Unfortunately, both methods are likely to produce debris and damage to people and objects around.

Method 1 occurs accidentally in chemistry labs when people neglect to dry the glassware thoroughly, and forget to use bumping stones (and sometimes in home cooking, where bumping stones are not usually used in the deep fryer).

Probably the safest method to demonstrate method 2 is to:

• use pure hydrogen gas (so the reaction occurs more slowly),
  
• put it in a balloon (so the explosion is not contained),
  
• hold a match under the balloon, using tongs and safety goggles
  
• and rather than do it yourself, watch it on Youtube, eg:

[syhprum]

A balloon inflated with acetylene makes a nice big sooty bang.

[Lab Rat]

One could create a small steam explosion by simply superheating very pure water in an open container inside a microwave and dropping in an object such as a sugar cube.  The sugar cube causes the liquid water that is at a much higher temperature than the boiling point to flash vaporize.  Few strings attached, though:
1. Sure you will be able to hold it in your hand, but you will, also, be able to acquire (at least) second degree burns on your hand fairly quickly from that scalding hot container.  []
2. This would give new meaning to steam bath.
3. The medical bills to repair you scalded body after taking a "steam bath" and having superheated water splashed on you may just enable your doctor to put his children through college.  []

Here's a video of the Mythbusters actually performing the experiment:
http://www.youtube.com/watch?v=1_OXM4mr_i0