i always taught that substances expand when they are hot and contract when they are cold. But when i was a kid i remember doing ann "experiment". On a cold winter night, i filled a cup almost to the brim with water and put it outside overnight. Then when i woke up the next morning, the cup was filled with ice to the brim. this means that the water expanded as it froze. I’m confused. Please clarify this for me.
thanks in advance
H2O is a polar molecule. The oxygen carries a partially negative charge because it is more electronegative (attracts electrons more strongly) than hydrogen. The two hydrogen atoms then consequently get a partial positive charge. When water solidifies (becomes ice), the molecules have to get arranged so that the same charge interactions are at a minimum. This means that the molecules have to stop moving and they end up expanding.
While water is still liquid molecules can move freely and once they repel each other they just move away. If they are about to solidify, they can’t move freely anymore which is why you end up with a greater volume.
If water didn’t have this property, there would be no life on earth. Ice forms on top of lakes/seas/rivers and insulates the lower parts so thus it maintains the life underneath.
standard GSCE work, husband says its in all the text books, and also on the internet… do your own ground work, he says, yes they do…type expanstion of liquids, type into google…. and heypresto…????
References :
H2O is a polar molecule. The oxygen carries a partially negative charge because it is more electronegative (attracts electrons more strongly) than hydrogen. The two hydrogen atoms then consequently get a partial positive charge. When water solidifies (becomes ice), the molecules have to get arranged so that the same charge interactions are at a minimum. This means that the molecules have to stop moving and they end up expanding.
While water is still liquid molecules can move freely and once they repel each other they just move away. If they are about to solidify, they can’t move freely anymore which is why you end up with a greater volume.
If water didn’t have this property, there would be no life on earth. Ice forms on top of lakes/seas/rivers and insulates the lower parts so thus it maintains the life underneath.
References :
In general (I believe in any instance besides water, actually, but I wouldn’t put that one down on paper) all substances contract when they undergo solidification with the exception of water. Due to the phenomenon of hydrogen-bonding (partially positive hydrogen’s in one water molecule are attracted to partially negative oxygen’s in another water molecule), when liquid water is cooled, it will expand. Additionally, ice is less dense than water, another trait that is either exceedingly rare or exclusive to H2O.
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