Question:
How does salt help the snow melt?
Answer:
The top layer of snow often has more active molecules than the snow that is deep within. Exhaust from cars, human activity and exposure to air and light can help make this outer layer more active, or warmer. So a little of the snow is no longer in a frozen state but has become liquid. When the salt is sprinkled on the ice or sow, it starts reacting with this liquid part. As the salt combines with the water, energy is released, and the next layer of tightly packed molecules is slightly warmed. Now that layer can interact with the salt as well. Since saltwater freezes at a lower temperature than pure water, the dissolving and melting can continue despite the cold. For good results, though, the temperature should be above 20 degrees.