Why does salt “melt” ice but freeze ice cream?

Question

A student asked me this today. I understand that salt doesn’t actually melt ice, but lowers its melting temp, but how do I explain this to a child?

In: 3

Answer 1

At 0°C, both ice and salt are solid. But because of some insanely weird chemistry, salt water needs to be made much colder to freeze solid. This is due to how the sodium and chlorine ions interact with the polar water molecules and there’s really no child friendly explanation. Salt and water don’t like to sit still when they’re together so they stay liquid