2006-09-12 05:48:35 · 10 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
The salt melting ice and frezing ice cream effects are both due to the fact that salt makes water freeze at a lower temperature. Sof you sprinkle salt on an icy sidewalk, it softens and melts the ice and you can clen it up easily.
With ice crea, the secret is the fact the salt is not actually IN the ice cream: it's sprinkled in the ice water in the OUTSIDE bucket. The ice is colder than freezing (it's frozen, of course) and the water, before the salt, can't drop below 0°C without freezing, itself. But, the water CAN get colder if you add salt to it, and this makes the ice cream cold enough to freeze where the salt is absent.
2006-09-12 05:55:48 · answer #1 · answered by poorcocoboiboi 6 · 1⤊ 0⤋
Salt lowers the freezing point of the water. On the sidewalk it makes it a lower temp that the ice can freeze at, so if it is above that it melts. In making ice cream you want to get the temperature lower than the 32F of ice, so add salt and lower the freezing point of the water so that the ice cream is subjected to a lower temp to freeze.
2006-09-12 07:51:12 · answer #2 · answered by science teacher 7 · 0⤊ 0⤋
The salt does not freeze with ice when making ice cream -- it forces the ice to melt, which reduced the temperature of the mixture. Either on the road or in the freezer, the salt lowers the melting point of the ice, which on the road may be enough to get it to melt away. Any solute will lower the melting point of ice; salt is used because it has two ions per molecule (it's the number of ions that counts) and it's cheap.
2006-09-12 06:20:16 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Salt decreases the freezing point of water. It does not melt ice but prevents water from freezing at 0 deg C. In ice cream, salt acts as an insulator.
2006-09-12 06:03:30 · answer #4 · answered by ag_iitkgp 7 · 0⤊ 0⤋
It lowers the freezing point. On the sidewalk the ice melts since it must be colder for it to remain frozen. For making ice cream the water becomes colder since the ice will melt at a lower temperature.
2006-09-12 05:51:18 · answer #5 · answered by Barkley Hound 7 · 0⤊ 0⤋
Salt lowers the freezing point, and therefore melts ice faster -- in BOTH cases.
But in order to melt, ice must still accept heat from somewhere. On your sidewalk, the heat is accepted from the air. But in the ice-cream maker, the heat is accepted from the mixture inside the churner. So as the ice melts faster on the outside, the mixture on the inside gets colder faster. It's working as a primitive heat-pump.
2006-09-12 06:03:45 · answer #6 · answered by Keith P 7 · 1⤊ 0⤋
Salt effectively LOWERS the freezing point. For sidewalks and ice cream-making. It makes sense for both, doesn't it?
Think it over!
2006-09-12 05:57:26 · answer #7 · answered by rvrjff 2 · 0⤊ 0⤋
Does the salt itself really melt the ice? I assumed that the additional friction when people walk on salted ice caused the ice to melt.
2006-09-12 05:50:28 · answer #8 · answered by mollyneville 5 · 0⤊ 0⤋
Concerning ice cream, I believe it draws excess moisture out of the mixture.
2006-09-12 05:54:35 · answer #9 · answered by powhound 7 · 0⤊ 2⤋
its two different kinds of salt isn't it?
2006-09-12 05:54:29 · answer #10 · answered by sha scrilla 3 · 0⤊ 1⤋