juno asked in Science & MathematicsChemistry · 1 decade ago

why doesnt water kept in a glass freeze even when d room temp drops below zero degrees?

freezing point of water being zero degrees.

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  • 1 decade ago
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    Unless there's something mixed with the water that stops it from freezing, the water will eventually freeze. Remember, matter needs to loose energy to drop its temperature... it needs to lose even more to change its state from liquid to solid.

  • 1 decade ago

    There are several reasons:

    1) Freeing isn't 100% due to temperature, but to something called vapor exchange, which can speed up or slow down the water's cooling to ambient temperature. The glass is fairly solid and is preventing vapor exchange on most sides. (This is also why water put outside in a wooden pale will freeze faster than water put outside in a glass bowl.

    2) We don't drink water, but a suspension of all sorts of things in a mostly water base. YOur water has a little salt, a little iron from the pipes, chlorine, sodium fluoride, etc. in it. That's going to drop its freezing temperature a bit.

    3) Water freezes at 0 only at sea level. Altitude changes the freezing temperature.

    4) Air cools faster than water. Give it time to catch up, and if the air temperature is a little below 0 the water will start to freeze.

  • 1 decade ago

    There are three reasons off the top of my head:

    1. The glass has mild insulative properties, keeping the water a little above zero.

    2. Water itself is denser than air, and thus retains heat longer than air. You'll need to give it awhile.

    3. You might be holding the glass of water, using your own body heat to keep it above zero (I've done dumber things in a lab).

  • 1 decade ago

    But, if you stir the water, it will be frozen instantly. That is a common phenomenon called super cooling. This is due to

    1) poor heat conductivity of water and

    2) anomalous expansion of water.

    Water is most dense at 4 degree centigrade. So when your room temperature drops, it will attain the most dense state first. Being a poor conductor of heat, further reduction of heat will only affect its surface. The main mass of water remains at 4 degrees.

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  • 1 decade ago

    who told you water wouldn't freeze in a glass when the temperature drops below zero degree...

    as a kid my bedroom was cold...many nights the water in my glass by my bed would freeze solid... even the glass in the window panes would have ice on them of a morning...........

  • 1 decade ago

    because it is kept in a glass

  • 1 decade ago

    it does, eventually.

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