How long does it take to boil water in a microwave?

[Cattlegod]

Originally posted by: mundane

Originally posted by: Jahee

Originally posted by: jagec

Originally posted by: rh71
Wasn't there a vid / warning that you should be extremely careful when boiling water in the microwave ? When you disturb it afterwards, it can "explode", causing it to splatter all over your hands/face.

Now I've never really understood that because people mic soups in there all the time.

Since a modern ceramic mug is pretty smooth, and drinking water is clean, what happens is that there are no good places for bubbles to form, so the water can actually be superheated at atmospheric pressure. As soon as you add nucleation sites (add cocoa, a spoon, sugar, whatever), suddenly a whole lot of that superheated water will flash to gas. You're supposed to put a scratch on the inside of a test tube before you boil anything in it, for the same reason.

Soups aren't a problem because they have plenty of nucleation sites.

Superheated i.e what temp?

This brings me to another question, as a chemist i should know really, but what causes the bubbles in boiling water, surely it cant be the oxygen bubbling off, because there would be H+ flying around, unless it forums H2O2? 😕
I'm probably way off, anyone explain?

I would expect that in the process of 'boiling', you expect some liquid water to change into the gaseous state. But I could be wildly wrong there as well.

here is a guess of what i think happens. h2o has a slight charge IIRC and without any sharp edges (particles or scratches in glass) to disturb the molecules, they will all line up to make sure all the charges of the water molecules are the strongest between each other. this accomplishes the effect of creating strong bonds between all molecules in the water, vastly increasing the boiling point (more energy is required to break the bonds between the water molecules). However, once you add a scratch to the glass, or add something to the water, the water molecules are no longer perfectly lined up with each other and will not have the bonds preventing them from turning into gas.

 

[50cent1228]

Originally posted by: jagec
Wow. I'm tempted to start a thread entitled "How should I hold my pecker when I pee?"

do it do it do it!

 

[Cerpin Taxt]

Originally posted by: Jahee

This brings me to another question, as a chemist i should know really, but what causes the bubbles in boiling water, surely it cant be the oxygen bubbling off, because there would be H+ flying around, unless it forums H2O2? 😕 but then thats poisonous?
I'm probably way off, anyone explain?

Gaseous water, i.e. steam.

 

[Jahee]

Originally posted by: jagec

Originally posted by: Jahee
Superheated i.e what temp?

This brings me to another question, as a chemist i should know really, but what causes the bubbles in boiling water, surely it cant be the oxygen bubbling off, because there would be H+ flying around, unless it forums H2O2? 😕
I'm probably way off, anyone explain?

I honestly don't know about the temperature. It might be interesting to try and measure it using an IR thermometer...but that would also be a bit risky.

As for the bubbles, that used to confuse me too, until I realized that they were (of course!) bubbles of gas-phase water. Nothing else.

Ahh, its quite confusing thinking about it... but yea it does make sense!

 

[50cent1228]

1 min 30 secs

 

[SonnyDaze]

140*F water from the tap and 2 min in the microwave. 🙂

 

[Jahee]

Originally posted by: Cattlegod

Originally posted by: mundane

Originally posted by: Jahee

Originally posted by: jagec

Originally posted by: rh71
Wasn't there a vid / warning that you should be extremely careful when boiling water in the microwave ? When you disturb it afterwards, it can "explode", causing it to splatter all over your hands/face.

Now I've never really understood that because people mic soups in there all the time.

Since a modern ceramic mug is pretty smooth, and drinking water is clean, what happens is that there are no good places for bubbles to form, so the water can actually be superheated at atmospheric pressure. As soon as you add nucleation sites (add cocoa, a spoon, sugar, whatever), suddenly a whole lot of that superheated water will flash to gas. You're supposed to put a scratch on the inside of a test tube before you boil anything in it, for the same reason.

Soups aren't a problem because they have plenty of nucleation sites.

Superheated i.e what temp?

This brings me to another question, as a chemist i should know really, but what causes the bubbles in boiling water, surely it cant be the oxygen bubbling off, because there would be H+ flying around, unless it forums H2O2? 😕
I'm probably way off, anyone explain?

I would expect that in the process of 'boiling', you expect some liquid water to change into the gaseous state. But I could be wildly wrong there as well.

here is a guess of what i think happens. h2o has a slight charge IIRC and without any sharp edges (particles or scratches in glass) to disturb the molecules, they will all line up to make sure all the charges of the water molecules are the strongest between each other. this accomplishes the effect of creating strong bonds between all molecules in the water, vastly increasing the boiling point (more energy is required to break the bonds between the water molecules). However, once you add a scratch to the glass, or add something to the water, the water molecules are no longer perfectly lined up with each other and will not have the bonds preventing them from turning into gas.

You're probably right with that guess there! Good explanation. :thumbsup:

 

[AznAnarchy99]

What ever you do dont put cooler water back into the glass if you need more water. I posted a thread about what happened to me when i did... exploding glass