Ask Dr Spaulding

[JPaul]

howcome hot water can freeze faster than cold water

What

[bigboab]

What Actually Happens

There are several things that help the hot waterl freeze faster than the cold water. Here are what is thought to be the most significant factors:

Layer of ice forms on the top of the cold water.

The hot water is more likely to be supercooled. This means that the hot water's temperature is more likely to cool to temperatures below zero degrees Celsius. In the cold non-supercooled water, ice crystals form and float to the top, forming a sheet of ice over the top of the water, creating an insulating layer between the cooler air and the water. This ice sheet also stops evaporation. In the hot water that has become supercooled (thus, no longer hot) the water, when it does freeze, freezes throughout, creating more or less of a slush before freezing solid.

Why is hot water more likely to be supercooled? Because hot water is less likely to contain tiny gas bubbles. Gas bubbles form from dissolved gasses as the water cools. When the hot water was heated, these dissolved gasses may have been driven out. In cold water, ice crystals use the tiny bubbles as starting points for formation (in physics, we call them nucleation points). But in the hot water, there are no bubbles, so there aren't as many starting points for the ice crystals.

Dissolved gasses also lower the freezing point. Since heated gas is less likely to contain dissolved gasses, it's more likely to freeze first.

Simple really.

[Biggles]

What Actually Happens

There are several things that help the hot waterl freeze faster than the cold water. Here are what is thought to be the most significant factors:

Layer of ice forms on the top of the cold water.

The hot water is more likely to be supercooled. This means that the hot water's temperature is more likely to cool to temperatures below zero degrees Celsius. In the cold non-supercooled water, ice crystals form and float to the top, forming a sheet of ice over the top of the water, creating an insulating layer between the cooler air and the water. This ice sheet also stops evaporation. In the hot water that has become supercooled (thus, no longer hot) the water, when it does freeze, freezes throughout, creating more or less of a slush before freezing solid.

Why is hot water more likely to be supercooled? Because hot water is less likely to contain tiny gas bubbles. Gas bubbles form from dissolved gasses as the water cools. When the hot water was heated, these dissolved gasses may have been driven out. In cold water, ice crystals use the tiny bubbles as starting points for formation (in physics, we call them nucleation points). But in the hot water, there are no bubbles, so there aren't as many starting points for the ice crystals.

Dissolved gasses also lower the freezing point. Since heated gas is less likely to contain dissolved gasses, it's more likely to freeze first.

Simple really.

Err... like I said, the cold water is trying too hard.

[bigboab]

I think we should ask Snny to try it out. A pail of hot water and a pail of cold water and sit them outside. Maybe a pail of drink for Snny to keep him warm while the water is freezing.

[TheYogi]

I dream of Red Admiral Butterflies skating in Moscow....................


TheHuhYogi

[bigboab]

I dream of Red Admiral Butterflies skating in Moscow....................


TheHuhYogi

Please Yogi. I will go to bed dreaming of you in a tutu carrying a big net and prancing about in the meadow chasing butterflies.

I dont think these new pills are working. do you? :crying:

[wacko jacko]

I recieved a PM today from a young man who will remain nameless, but it's a question i'm sure many of you will have wanted to ask, it went:

"Hey, how come there aren't gynecologists for men? Woot Woot!"

My reply? I don't know, and i certainly wish there were, because men need sexual healthcare, too. If you are male and have a sexual health concern, you can address it with your regular doctor. There are specialists who deal with urology and oncology, as well as other areas of male sexual healthcare.

Does that help?

whats my out come i know you see it

[Dr Spaulding]

whats my out come i know you see it

not very good, unless you stop grabbing yr nutsack at every oppurtunity.

[sArA]

um, whose the doctor here btich, me or you?

erm....well...actually.....

[GepperRankins]

time to use those jungle book mugs