How does salt melt ice?


My child asked me this question and I struggled to explain it in terms he could understand.

In: 2

Im going to do my best. Salt lowers the freezing point of water. Think of regular water as little balls, the temperature dropping is like trying to put the balls into a small box and when they can’t get any closer they become ice. Salt are smaller balls that get in between the water and make it so that it has to be colder for the water to become ice.

Ice is constantly melting a refreezing (that’s how icicles happen).

When you put salt on the ice, the water that just melted dissolves some of that salt and becomes salt water. Salt water has a lower freezing point than fresh water, so it’s not able to freeze again.

Imagine the ice molecules are like Lego bricks tightly stacked together. When you add salt, it’s like inserting a layer of very small slippery marbles between the Lego bricks. This makes it harder for the bricks to stick together, and they start to loosen up and slide around, causing the ice to melt.

That’s why we use salt on icy roads and sidewalks during winter, it helps melt the ice, making it safer to walk and drive on.