How is ice melted by slat?
Posted on: May 29, 2015
Did you know that every year councils up and down the country spend approximately £150 million spreading 2 million tonnes of salt across the UK's many motorways, trunk roads and main roads? On top of that it is likely that as home and business owners you will have also spread salt across your car parks, walkways, patios and driveways.
When ice begins to form we all instinctively reach for the salt from the cupboard and it is something we do without thinking. But why salt and how does it cause the ice to melt?
The Scientific Bit…
At school we were all taught that ice forms when the temperature of water falls to 0°C (32°F). Well, when you add salt to liquid water it causes the salt to dissolve and the freezing point of the water to fall. The more salt you add, the lower the temperature at which the water will begin to freeze. For example:
- A 10 percent salt solution reduces the point at which water freezes to -6°C (20°F)
- A 20 percent salt solution reduces the point at which water freezes to -16°C (2°F)