Do you know how salt melts snow?
Grit is often sprayed on roads to stop cars skidding on very cold days. What we call grit is actually a mixture of salt, gravel and stone.
When snow falls on a road with grit applied it mixes with the salt, which lowers the freezing point of the snow stopping ice forming.
Water with salt added freezes about 5 degrees lower than water with no salt.
To be most effective grit must be dropped onto surfaces before they freeze.
How does salt melt snow – Investigation Ideas
Freeze a solution of salt and water
Try freezing water with salt added and plain water in an ice cube tray. The salty water won’t freeze.
Try sprinkling a little salt on the plain water ice cubes. Watch what happens.
Make an icy road
Freeze two sheets on ice. Sprinkle salt and sand on one and leave the other. Watch what happens to the two surfaces.
Try rolling a toy car over both surfaces, is one more slippy?
Melt an ice sculpture
The Artful Parent has a beautiful ice sculpture you can melt with salt too!
Now you know how salt melts snow!