Wednesday, January 12, 2011


It's a snow day! The schools, my husband's university, and my work are all closed today thanks to the almost 30 cm or 12 inches of snow we've had fall in the last 11 hours. The roads are treacherous and it's too dangerous to go out today. So SNOW DAY! (And tomorrow's going to be worse with freezing rain predicted to add that crunchy layer to the powder! EEK!)

Traditionally, Chilliwack has used salt to clear our roads as it is good to about -18˚C or 0˚F (and it rarely gets below -7˚C around here), but this year they've started using a different concoction, one that includes propylene glycol or other glycols to reduce the freezing point of water (other communities have used this type of thing for years, but we're finally getting around to it!).

As a note, most of our humectants can work as de-icers by reducing the freezing temperature of water, but I don't think you want to throw a ton of Hydrovance onto your windshield any time soon (mainly due to cost). 

You can also use different types of salts to melt snow or weaken ice. Good old sodium chloride (NaCl, known as table salt or rock salt) will work because a brine solution (water mixed with salt) will lower the freezing point of water, but it can cause a lot of rust on our cars and corrosion in other metallic things. Calcium chloride (CaCl2) is being used a lot lately because it doesn't have the same effect on the environment (although it's not very evergreen tree friendly) and because it is good to really low temperatures (we're talking -52˚C or -82˚F as opposed to -18˚C for NaCl).

Unfortunately, no matter what de-icer you use, there are consequences for our environment. Urea can break down into ammonia, which can be toxic for animals. Salt can cause corrosion, and calcium chloride can upset our trees, and propylene glycol takes a long time to biodegrade and consumes oxygen as it breaks down.

See, even a snow day can be made more interesting with chemistry!


Tara said...

I'm thinking I need to move to Chilliwack...I wish it never got below -7C here. It's minus 24C in Edmonton right now and the snow is never ending!!

Susan Barclay-Nichols said...

I'm sure you think we're big wusses out here...a little snow and everything shuts down, but we're not used to it! And it really is a different kind of snow. It's very wet and slippery and it'll melt later today when the rain starts, which leads to horrible slush, which will freeze tonight and make things worse!

I love the snow! Raymond and I flew to Calgary in the middle of December a few years ago to enjoy the snow that we weren't getting out here. It was -11˚C and we walked for hours in it. But we were tourists!

melian1 said...

thanks for making snow and ice more interesting! we've got our second major winter storm here with snow and ice and dangerous roads, too, and we're even less used to it than you are! southeastern us rarely gets much in the way of snow and ice.

but today's blog was very interesting!

Babou16 said...

Lucky you! I can still see some green on our lawn and I live near Montreal ! This lack of snow is soooo frustrating....

But thanks for the chemistry of de-icers. Maybe using sand on smaller roads would be better?

Anonymous said...

We have snow here in Finland too. About 60 cm there where I live. We must go to work and school, although it´s snowing or if we have cold 35- 40 degrees.

Susan Barclay-Nichols said...

Like I said, I know some people think we are such big babies - a little snow and the world shuts down - but we aren't used to it. People don't tend to have snow tires, the roads aren't cleared, and it's a wet snow that compacts down into ice very quickly. It rained all afternoon and night last night, so we have slush as far as the eye can see, which is going to make for great fun driving today!

Oh, and our furnace konked out and it's about 15˚C in the house. I can't wait to take my morning shower and leave the house with wet hair! (It takes about an hour to blow dry and I look like a freak, so that's not an option!)