{"id":756,"date":"2019-02-02T12:53:25","date_gmt":"2019-02-02T16:53:25","guid":{"rendered":"http:\/\/blog.richmond.edu\/pollocklab\/?p=756"},"modified":"2019-02-02T12:53:25","modified_gmt":"2019-02-02T16:53:25","slug":"a-commentary-on-the-conversation","status":"publish","type":"post","link":"https:\/\/blog.richmond.edu\/pollocklab\/2019\/02\/02\/a-commentary-on-the-conversation\/","title":{"rendered":"A commentary on “The Conversation”"},"content":{"rendered":"

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It is my belief that as scientists we have a responsibility to communicate, present, and discuss with the general public about scientific matters. To educate them on the things we know in an informative, respectable, and positive way. “The Conversation” is a website that publishes news stories\/articles on a variety of different topics, including science, written by experts in their fields. When the University of Richmond media folks (Hi Sunni!) approached me to be a part of The Conversation community, I immediately felt like it aligned with my passions and responsibilities. Yesterday my first article was published on their site. I am republished it here with their permission. Enjoy!<\/strong><\/em><\/p>\n

~jap<\/strong><\/em><\/p>\n

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Salt doesn’t melt ice \u2013 here’s how it actually makes winter streets safe<\/h1>\n
\"File 
Spraying salt onto roads is a safety measure.
\nstoatphoto\/Shutterstock.com<\/a><\/span><\/figcaption><\/figure>\n

Julie Pollock<\/a>, University of Richmond<\/a><\/em><\/p>\n

Brrr \u2026 it\u2019s cold out there! Children are flocking to the television in hopes of hearing there will be a snow day; the bread and milk aisles at grocery stores are empty because of an impending snow storm; and utility trucks are out spraying salt or salt water on the roads.<\/p>\n

We all know why the first two happen \u2013 kids are excited for a day off of school filled with hot chocolate and snowmen. Adults are stocking up on necessities. But what\u2019s up with those trucks?<\/p>\n

They\u2019re working to protect drivers from slippery conditions by spraying rock salt or a solution of salt water<\/a> to prevent ice formation. This salt is very similar to the salt you have on your dinner table \u2013 it\u2019s the same sodium chloride, NaCl. There are some proprietary mixtures that contain other salts \u2013 such as potassium chloride (KCl) and magnesium chloride (MgCl) \u2013 but they\u2019re not as commonly used.<\/p>\n

Road salt isn\u2019t as pure as what you use on your food; it has a brownish gray color, mostly due to mineral contamination<\/a>. Subjecting the environment to this salt via runoff can have some unintended consequences including negative effects on plants, aquatic animals and wetlands<\/a>.<\/p>\n

But it\u2019s a cheap and effective way to protect roads from ice due to a simple scientific principle: freezing point depression of solutions<\/a>. The freezing point of pure water, the temperature at which it becomes ice, is 32 degrees Fahrenheit. So if there\u2019s snow, sleet or freezing rain and the ground is 32 F or colder, solid ice will form on streets and sidewalks.<\/p>\n

If the water is mixed with salt, though, the freezing temperature of the solution is lower than 32 F. The salt impedes the ability of the water molecules to form solid ice crystals. The degree of freezing point depression depends on how salty the solution is.<\/p>\n

\"\"<\/a> 
Salt prevents the water molecules from solidifying into ice crystals at 32 F, instead staying slushy at that temperature, before eventually freezing around 15 F.<\/span>
\nJulie Pollock<\/span>, CC BY-ND<\/a><\/span><\/figcaption><\/figure>\n

It\u2019s important to note that the salt must be in a solution with liquid water in order for this principle to be obeyed. That\u2019s why many cities spray a salt solution before any ice forms.<\/p>\n

Salt that\u2019s dumped on top of ice relies on the sun or the friction of car tires driving over it to initially melt the ice to a slush that can mix with the salt and then won\u2019t refreeze. Pre-treating with solid salt relies on the warmer road surface to initially melt any snow or freezing rain so that it can properly mix with the salt. This is also why pre-treatment of bridges \u2013 which are colder than other roads \u2013 does not typically work, and why you see \u201cbridge freezes before road\u201d signs.<\/p>\n

These salt solutions decrease the freezing temperature of water to around 15 F<\/a>. So, unfortunately for folks facing truly frigid temps, treating with salt won\u2019t get rid of ice on their roads.<\/p>\n

An alternative strategy used at these lower temperatures is putting sand on the ice. Sand doesn\u2019t change the melting temperature, it just provides a rough surface for your tires to prevent slipping and sliding.<\/p>\n

\"\"<\/a> 
A de-icing cocktail of brine and beet juice, which could potentially work in temperatures as low as minus 25 F.<\/span>
\nAP Photo\/Gene J. Puskar<\/a><\/span><\/figcaption><\/figure>\n

The science of freezing point depression can be applied to any solution, and many research groups have focused on developing alternatives with fewer negative environmental consequences<\/a>. They include additives such as molasses and beet juice<\/a>. So maybe you can look forward to cleaning not just white salt off the bottom of your jeans after a winter walk, but pink salt as well.\"The<\/p>\n

Julie Pollock<\/a>, Assistant Professor of Chemistry, University of Richmond<\/a><\/em><\/p>\n

This article is republished from The Conversation<\/a> under a Creative Commons license. Read the original article<\/a>.<\/p>\n

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\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div> It is my belief that as scientists we have a responsibility to communicate, present, and discuss with the general public about scientific matters. To educate them on the things we know in an informative, respectable, and positive way. “The Conversation” is a website that publishes news stories\/articles on a variety of different topics, including […]<\/p>\n","protected":false},"author":2906,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[795,49580],"tags":[],"class_list":["post-756","post","type-post","status-publish","format-standard","hentry","category-blog","category-the-conversation"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/blog.richmond.edu\/pollocklab\/wp-json\/wp\/v2\/posts\/756","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.richmond.edu\/pollocklab\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.richmond.edu\/pollocklab\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.richmond.edu\/pollocklab\/wp-json\/wp\/v2\/users\/2906"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.richmond.edu\/pollocklab\/wp-json\/wp\/v2\/comments?post=756"}],"version-history":[{"count":0,"href":"https:\/\/blog.richmond.edu\/pollocklab\/wp-json\/wp\/v2\/posts\/756\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.richmond.edu\/pollocklab\/wp-json\/wp\/v2\/media?parent=756"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.richmond.edu\/pollocklab\/wp-json\/wp\/v2\/categories?post=756"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.richmond.edu\/pollocklab\/wp-json\/wp\/v2\/tags?post=756"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}