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The Chemistry of Road Salt And How It Works

by LabNotes

What’s the difference between the salt applied to our roads in winter and the salt in your salt shaker?

Not a lot. Road salt – or rock salt – is halite, the mineral form of sodium chloride (NaCl) as it is naturally mined. Table salt is just a purified version of the same mineral.

Road salt still contains mineral impurities that can make it grey or brown in color. It may include additives like sodium hexacyanoferrate and sugar that help trucks deliver it to roadways without caking.

Road salt lowers the freezing point of water, making it more difficult for water to freeze and create dangerous driving conditions.

This only works when there is a small amount of water present during application, so it’s common for roads and sidewalks to be coated with brine – a road salt and water mixture – when cold weather is in the forecast. A good application before a winter storm can decrease the amount needed to de-ice the roads after the event.

Road salt is the most popular option for de-icing, but occasionally sand and other chemicals can be used, particularly on sidewalks. Among the producers of the product is American Chemistry Council member Occidental Chemical Corporation which has a whole business sector devoted to Calcium Chloride and its many uses. Check out their website!

The effectiveness of road salt to prevent accidents and injuries is undeniable. The American Highway Users Alliance found that applying it to the roads reduces accidents up to 93%.

With many Americans still living under wintery conditions, we’re betting you’re grateful for the road salt and its benefits!

American Chemistry Council

The American Chemistry Council (ACC) represents the leading companies engaged in the multibillion-dollar business of chemistry. ACC members apply the science of chemistry to make innovative products, technologies and services that make people's lives better, healthier and safer. ACC is committed to improved environmental, health, safety and security performance through Responsible Care®; common sense advocacy addressing major public policy issues; and health and environmental research and product testing. ACC members and chemistry companies are among the largest investors in research and development, and are advancing products, processes and technologies to address climate change, enhance air and water quality, and progress toward a more sustainable, circular economy.

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