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Sigh, it seems the summer is gone. Mornings are heavily cold, middays turns out hot, and then you freeze during the night. Which reminds me of something quite awkward about the water. – So, water is frigging everywhere. They even tell us we’re 65% water like we’re some sort of cucambers, or Pickle Ricks in the making, if you will. Water is misterious. We can’t survive more than two days without it, but the first thing you learn in school about it is that it has no color, taste or a smell. But it is essential. – It may come strange to you — water reaches its maximum density at 4°C. At that point, it is densier than when is in freezing mode, which is why standard ice floats on water. Why? — Because that is the one reason life on our planet has flourushed: If ice were denser than water, oceans and lakes would freeze from bottom up, almost certainly preventing the chemistry magic that makes life possible. Than there is one more cute little science headbanger. Mpemba effect. Or “how freezing ice cream almost 60 years ago put science in hot water”. . . . #popularscience #mpembaeffect #mpembaparadox #funchemistry #funfacts #water #neuronenvogue

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Sigh, it seems the summer is gone.
Mornings are heavily cold, middays turns out hot, and then you freeze during the night.
Which reminds me of something quite awkward about the water.
So, water is frigging everywhere. They even tell us we’re 80% water like we’re some sort of cucambers, or Pickle Ricks in the making, if you will.
Water is misterious.
We can’t survive more than two days without it, but the first thing you learn in school about it is that it has no color, taste or a smell.
But it is essential.
It may come strange to you — water reaches its maximum density at 4°C. At that point, it is densier than when is in its freezing mode, which is why standard ice floats on water.
Why? — Because that is the one reason life on our planet has flourushed: If ice were denser than water, oceans and lakes would freeze from bottom up, almost certainly preventing the chemistry magic that makes life possible.
Than there is one more cute little science headbanger. Mpemba effect.
Or “how freezing ice cream 50 years ago put science in hot water”.
Why does hot water freeze faster than the cold?
—-
The effect is named after its discoverer – Erasto Mpemba, who as a Tanzaian teenager in the ‘60s. During school cookery lessons, he was taught to make ice cream by heating milk and sugar together on a stove, then leave the mixture to cool before putting it in the freezer.
Mpemba noticed something weird: when he put the hot mixture straight into the freezer, it was ready faster than if it was left to cool down before.
Curious, Mpemba conducted a similar experiment using just water. He found that, like the ice cream, containers of boiling hot water seemed to take less time than cold water to freeze.
And really, WHY?
Oh, well. No single and correct answer here, I’m afraid.
Science is in awe regarding this strange paradox: from Aristotle, Francis Bacon and René Descartes to modern phisysicts.
Surprisingly, there is still no scientific consensus on the exact cause of the Mpemba effect.
One idea is that warm containers make better thermal contact with a refrigerator and so conduct heat more efficiently. Hence the faster freezing.
Another is that warm water evaporates rapidly and since this is an endothermic process, it cools the water making it freeze more quickly.
None of these explanations are entirely convincing, which is why the true explanation is still up for grabs.
It seems that has something to do with the bonds in the water. But, what’s so odd about the bonds in water? It is simple: a single water molecule consists of a relatively large oxygen atom joined to two smaller hydrogen atoms by standard covalent bonds. Yes? Yes. H2O
But put water molecules together and hydrogen bonds also begin to play an important role. 
Chemists have long known that these bonds are important. For example, water’s boiling point is much higher than other liquids of similar molecules because hydrogen bonds hold it together.
But in recent years, chemists have become increasingly aware of more subtle roles that hydrogen bonds can play
Maybe thay can explain the Mpemba effect?
As the liquid warms up, it forces the hydrogen bonds to stretch and the water molecules sit further apart. This allows the moleculular bonds to shrink again and give up their energy.
The important point is: this process in which the molecular bonds give up energy is equivalent to cooling.
But while this idea is convincing, it is not quite the theoretical slam dunk that many physicists will require to settle the question. It lacks predictive power. A solid solution needs to predict a new property of water that conventional thinking about water does not.
However, as people don’t currently agree on whether it exists or not, it currently can’t be exploited in this way – and as long as the effect remains a mystery, scientists will continue to seek an explanation. Yeeey.

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