If you place an ice cube in each of two glasses, one with fresh water the other with salt water both at room temperature, will either melt the ice more quickly and why?
Do your own thinking, no Googling.
Do your own thinking, no Googling.
I know the salt water will get colder and intuition tells me the salt water will melt the ice faster as it lowers the freezing point. After all salt is put on roads to prevent icing in wimpy countries like ours without real winters . But I know I have forgotten something from my chem lessons here so probably very wrong.
Will go google my ignorance now...
Will go google my ignorance now...
All: Please keep the findings to yourself after you look it up. There are suggestions on both sides of the argument out there but I believe only one correct answer. I plan to do the experiment later.
Don't worry I will, which is why I googled after posting my thoughts. However I am not firing on all cylinders at the moment as new arrival in the family.
Hi,
Without googling :
The transition temperature in the salt water is lower so the driving
thermodynamic difference is higher for salt water. Another way of
putting it is salinity will tend to equilibrium and the salinity delta
will tend to drive the melting process, by how much I don't know.
But the higher the salinity, the bigger the difference.
It will melt faster in salt water. I've no intention of looking it up.
rgds, sreten.
Without googling :
The transition temperature in the salt water is lower so the driving
thermodynamic difference is higher for salt water. Another way of
putting it is salinity will tend to equilibrium and the salinity delta
will tend to drive the melting process, by how much I don't know.
But the higher the salinity, the bigger the difference.
It will melt faster in salt water. I've no intention of looking it up.
rgds, sreten.
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Salt water has higher density, so should maintain its temperature better than fresh water under identical conditions; advantage - salt water. (EDIT: I was typing while sreten posted, but I think this goes hand in hand with his explanation, but in different words. 🙂 )
Also, there is a principal (which I am forgetting the name of) which basically states that substances with higher salt content (whether sodium-based or other) actively "draw in" substances of lower salt content. This is why salt or salt water is often used to "draw infection out" of a wound or similar, because salt water is far more saline than our bodies. Likewise, the salt water would actively be "drawing in" the ice cube. I am pretty sure this is the major enabler of cellular osmosis, but it has been a long time since I studied biology. 🙂
Advantage salt water, but I am sure the official explanation is far more eloquent than what I just wrote.
Also, there is a principal (which I am forgetting the name of) which basically states that substances with higher salt content (whether sodium-based or other) actively "draw in" substances of lower salt content. This is why salt or salt water is often used to "draw infection out" of a wound or similar, because salt water is far more saline than our bodies. Likewise, the salt water would actively be "drawing in" the ice cube. I am pretty sure this is the major enabler of cellular osmosis, but it has been a long time since I studied biology. 🙂
Advantage salt water, but I am sure the official explanation is far more eloquent than what I just wrote.
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Oh c'mon, what the heck is a salt water ice cube? Give your heads a gentle smack up the side and if
that doesn't work I have another suggestion.
that doesn't work I have another suggestion.
I should know better than to be so imprecise on this forum. 🙂
I meant something more along the lines of a teaspoon of table salt in a cup of water. 😉
Hi,
All ice is fresh water ice, as CW alludes to in post #10, and
so my comment in post #9, is a very brainless comment.
rgds, sreten.
All ice is fresh water ice, as CW alludes to in post #10, and
so my comment in post #9, is a very brainless comment.
rgds, sreten.
I have always been under the impression that the freezability of salt water is a function of temperature; that if the temperature is reduced enough, that salt water will freeze. Is this not the case?
If not, and if the human body is generally as saline as sea water, then how do corpses freeze?
Hi,
Ice crystals are formed, and the lower temperature is that
needed to force out the salt, so salt water freezes lower.
rgds, sreten.
Yes. I googled it. But that's not the end of the story.
The salt gets pushed out as the water freezes, which increases the concentration of salt in the remaining liquid water. Therefore the temperature needs to be reduced further to push that higher concentration of salt from the water, and so on. Near the end, the remaining liquid becomes supersaturated with salt and finally freezes at -21.1C. At least some of the ice cube then can be considered salty ice.
Either way, it might either make or break a cocktail. 🙂
(It could likewise be used in Cal's experiment)
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