If salt mixed in ice lowers the melting pt how does it work in the two opposite cases as follows?

Question

We use salt with ice and use this mixture outside a metal pot to prepre icecream in it. Also salt is used for melting ice on the streets on snowy days . How are both things explained by assuming the fact that the melting pt of ice is lowered by mixing salt ?
In the first case ok but what about the second?

Answer 1

In ice cream, salt lowers the melting point of the ice mixture - so the temperature of the water bath surrounding the ice cream is less than 0 degrees Celsius (less than 32 Fahrenheit) so the ice cream freezes.

When salt is added to ice on the sidewalk, it also lowers the melting point - so the ice will melt if the temperature of the sidewalk is greater than the new melting point. Here's an example. If it is 20 degrees Fahrenheit outside, ice normally would not melt. But if you add salt to reduce the melting point to 15 degrees Fahrenheit, then the ice will melt because the temperature of the sidewalk (20 degrees F) is greater than the new melting point (15 degrees F).

Answer 2

Salt has both capacity of lowering of freezing point and elevation of boiling point. This is due to imbalance is the two phases of a liquid or water in local and ambient temperatures. When the surrounding temperature is higher than the ice, addition of salt to ice will help in freezing and if the surrounding temperature is lower than that of the ice, addition of salt to ice will help in melting. That is why during the winter (snowy season) when the surrounding temperature is lower than the ice, addition of salt to ice is required to melt. These phenomenon is only due to variations in the free energy of water according to the ambient temperature.

Answer 3

I'm not sure about this, but concerning the ice cream part, a salt solution in water will have a freezing point of water below zero Celsius (32 Fahrenheit). This would allow for whatever is inside the bowl to go below zero Celsius while the outside medium is in liquid form, which ensures homogenousness. As metal is a good conductor of heat, it makes sense from that point of view. (There are other liquids with lower freezing points than water that can theoretically be used, but I doubt that they would be good for food preparation.)

Answer 4

say the ice on the street is pure water and it froze at 0 degress f. now obviously the ice will start melting eventually because of people waliking over it and cars passing by etc, that will warm some oif it up. then you put salt on the streets, and it dissolves in this water. then the surrounding ice absorbs heat from the mixture and voila! the ice melts.