# why does fresh water freeze faster than salt water

Answer 1: While pure water freezes at 0`C (32`F), salt
water needs to be colder before it freezes and so it usually takes longer to freeze. The more salt in the water, the lower the freezing point. Very salty water freezes at around -21 `C, or about -6 `F. What is interesting is that this effect is used all over the place for practical reasons. Often, salt is put on roads to melt ice. If there's a lot of ice, you need a lot of salt. So then the question is why does salt water need to be colder to freeze than fresh water? Basically, ice is a crystal, an almost perfect array of pure water molecules with almost no salt in it. To make that out of pure water requires limiting the ways the water molecules move around. To make that out of salt water requires BOTH limiting the ways the water molecules move around AND limiting the ways the salt can move around (it's stuck in the liquid, or in separate crystals), which is harder to do.

Click to return to the search form. Isn't WONDERful? On a hot day, nothing goes down quite as well as lemonade poured over a glass full of cubes. In fact, makes so many things better. For example, we love to use to make homemade! When Old Man Winter comes calling, falling temperatures can turn creeks, lakes, ponds, and even rivers into frozen rinks you can on. But what about the? If you've ever been to the in the winter, you've probably noticed that it doesn't like a small might. So does the ever? If you've seen pictures of the North Pole or the South Pole, you know that there are caps in those places.

If the freezes in those areas, why doesn't the rest of the during the winter? The freezing point of is 0б Celsius or 32б Fahrenheit. The presence of in, though, reduces the freezing point of. The more in the, the lower the freezing point will be. When freezes, molecules of and have bonded together into a structure of. The presence of makes it harder for molecules to bond to the structure, because naturally repels molecules. So in a sense, the gets in the way of molecules, blocking them from joining the. The also bumps into the, knocking molecules off of the structure -- and that's how melts. When molecules displace molecules, the freezing rate slows down. This is why is often used on to slow down freezing and make them safer to travel upon.

Although the of varies, often has about 35 grams of for every 1,000 units of. This lowers the freezing point of to about -1. 8б C or 28. 8б F. So will. It just needs to reach a lower. Another factor that affects the freezing of is its. Unlike ponds, move around constantly. This helps retain heat. As a result, only really cold areas, such as the or South Pole, usually get cold enough for to. When freezes, though, only the part freezes. The molecules are pushed below the surface of the. As a result, ends up being that can be melted for drinking! About 15% of the contains sea for at least part of the year. That might not sound like a lot, but that amounts to about of sea!

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