Melting Snow and Ice

Posted by PITHOCRATES - February 5th, 2014

Technology 101

When Temperatures fall below Freezing Liquid Water turns into Solid Water

You know what the best thing about water is?  You don’t have to shovel it.  Well, that, and its life-giving properties.  Let’s face it.  We couldn’t survive without the stuff.  We couldn’t grow food.  We even couldn’t live without drinking water.  So perhaps its life-giving properties is the best thing about water.  But a close second would be that thing about not having to shovel it.

When it rains water soaks into our green areas.  It runs off driveways and sidewalks into green areas.  And into streets.  Where it runs off into a storm drainage system.  Which takes it to a river or lake.  The rain lets our gardens grow.  And any excess water conveniently just goes away.  We may have a puddle or two to slosh through.  But even those go away without us having to do anything.  Water is nice that way.  As long as the temperature is above its freezing point.

When the temperature falls below the freezing point of water bad things start to happen.  Liquid water turns into solid water.  And hangs around for awhile.  Accumulating.  On our driveways, sidewalks, porches and roads.  It’s pretty much everywhere we don’t want it to be.  Making it difficult to walk.  And drive.  We slip and fall a lot in it.  The sun may melt it a little during the day.  Creating puddles of water where the snow once was. But when the sun sets those puddles freeze.  And become even more slippery.  Making solid water more dangerous than liquid water.  So a big part of making it through winters in northern climes, then, is transforming solid water back into the liquid form.

Even though Bourbon melts Ice Cubes Bourbon would be a Poor Choice to melt Snow and Ice

All material can be in three different stages.  It can be a solid.  A liquid.  Or a gas.  What determines the phase of this material depends on a couple of things.  Mostly temperature and pressure.  And the chemical properties of the material.  At ambient temperature and pressure material typically exists stably in one phase.  Water, for example, is stable in the liquid phase on an 80-degree summer day.  Allowing us to swim in it.  While on a freezing February day it is stable in the solid phase.  Which is why we hold the Winter Olympics in February.  The cold temperatures give us the best solid water conditions.

If we raise the temperature of water we can turn it from a liquid to a gas.  We could also do this by lowering the ambient air pressure.  Such as putting it into a vacuum.  For a liquid remains a liquid as long as the vapor pressure (the tendency for particles to escape from the liquid they’re in) of the liquid is less than the ambient air pressure.  If we lower the ambient air pressure below the vapor pressure of the liquid we can lower the boiling point of that liquid.  This is why different liquids have different boiling points.  They have different vapor pressures.  Oxygen has a very high vapor pressure and requires a high pressure and cold temperature to keep oxygen in a liquid phase.

When we take ice cubes out of the freezer and add them to a glass of bourbon they melt.  Because the ambient temperature outside of the freezer is above the freezing point of water.  So the solid water changes its phase from solid to liquid.  It would follow, then, that pouring bourbon on snow and ice would help melt it.  Of course we don’t do that.  For wasting bourbon like that would be criminal.  Not to mention costly.  Even if you used the cheap stuff.  Making bourbon a poor choice for melting snow and ice.

Salt dissolves into a Brine Solution that lowers the Melting Point of Snow and Ice

We see that a material will change its phase at different temperatures and pressures.  Which is good to know.  But it doesn’t help us to melt snow and ice during winter.  For we can’t lower the atmospheric air pressure to lower the boiling and melting points of water.  And we can’t raise the ambient temperature above the melting point of water.  If we could our winters would probably be a lot more comfortable than they are now.  So because when we can’t change the air pressure or temperature of the ambient environment the snow and ice is in we do something else.  We use chemistry to lower the melting point of snow and ice.  And the most common chemical we use is salt.

To melt snow and ice salt needs heat and moisture.  The moisture comes from the snow and ice.  Or from the humidity in the air.  The heat comes from the warmth of the earth or air.  Heated by the sun.  It also comes from the friction between tires and the road.  When salt comes into contract with water and heat it dissolves into a brine solution.  And this brine solution has a much lower melting point than water.  Which in turn lowers the melting point of the snow and ice it comes into contact with.  Allowing it to be in the liquid phase at temperatures below freezing temperatures.  Melting that snow and ice so it can run off like rain water.

The warmer it is when it snows the quicker salt will melt that snow.  While the colder it is the longer it takes to melt.  If it gets too cold (around 15 degrees Fahrenheit) salt proves to be ineffective.  In temperatures below 15 degrees Fahrenheit other chemicals work better.  Such as calcium chloride.  But calcium chloride is more costly than sodium chloride (salt).  Ambient temperatures, time of day, sunny or cloudy, wind, etc., all determine the chemical to use.  And the amount of chemical to use.  They consider all of these factors (and more) before sending those ‘salt’ trucks out on the roads.  Allowing us to drive in the worst of winters just as we drive in the best of summers.  It may take more time.  And there may be a little more cussing.  But we still go to work, take our kids to school, go shopping, etc., when it snows.  Thanks to chemicals.  Chemistry.  And the people that put those chemicals and that chemistry to work.


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FUNDAMENTAL TRUTH #42: “Romantics often don’t have a clue of what they romanticize about.” -Old Pithy

Posted by PITHOCRATES - November 30th, 2010

A Lady like Scarlet O’Hara no doubt Smelled of Ass and Armpit

Some people just don’t like modern times.  Like environmentalists.  Who say things were better before man industrialized everything.  Back before the big cities.  When things were quaint.  Like on that great plantation, Tara, in Gone with the Wind

Yes, things were simpler then.  And better.  There was no plastic.  Or glass and steel skyscrapers.  Or indoor plumbing.  If you had to poop during the night, you just squatted over a bowl.  That quaint, little chamber pot.  Which you either dumped out of your window.  Or left on the bureau until the following morning.

Of course, you didn’t shower every day back then.  Even the wealthy.  Even someone like Scarlet O’Hara.  Who no doubt smelled of ass and armpit.  But things were better back then.  Simpler.  And the environment was cleaner.

Once Upon a Time, Our streets were filled with Poop and Urine

Well, perhaps cleaner is not the word.  Let’s say more natural.  Back before polluting cars and that big-ass carbon footprint, the internal combustion engine, we used horses.  We rode them to get from here to there.  And we used them for work.  And there was no gasoline or polluting products of combustion.  Carbon monoxide.  A horse ate what grew naturally.  The way things should be.  And pooped and peed all over the place.

You ever go to a quaint touristy area with a historic part of town?  Where you can take a cozy moonlight ride in a horse-drawn carriage?  They try to be authentic.  But they throw in a few modern conveniences.  Like a poop bag under the horse’s butt.  To keep the street clean of horse poop.  And free of flies that are attracted to the horse poop. 

In the good old days, the streets were full of horses.  Horse poop.  Horse urine.  And flies.  A lady in here finest Sunday-go-to-meeting dress dragged her dress through those streets.  And the filth in them.  And if she walked on the sidewalks she probably dragged that dress through human poop and urine.  From all those chamber pots poured out from the windows above.  And the flies were everywhere.

To Protect Children in Africa from DDT, We let them Die from Malaria

Then man had to come along and ruin everything.  They took a plow to paradise and built cities.  They paved the streets.  After installing storm drains first.  Little creeks and wetlands disappeared.  As did malaria.

Say what you will about the cities, but a concrete jungle does not breed mosquitoes.  You know what does?  Jungles.  Swamps.  Wetlands.  And you know what mosquitoes breed?  Malaria.  But thanks to America’s concrete jungles (a.k.a., the big cities), we don’t have a malaria problem.

You know who does?  Africa.  Big time.  Because they’re still very much that pristine paradise the environmentalists pine for.  And a mosquito breeding ground.  There’s wholesale dying there because of these little buggers.  And what are we doing about it?  We’re sending them mosquito netting to sleep under.

There was a time, though, when we held the mosquitoes at bay in Africa.  We saved lives with DDT.  By killing mosquitoes wholesale.  But Rachel Carson wrote a book called Silent Spring.  And it did to DDT what the movie The China Syndrome did to nuclear power.  Some countries still use it (India, China and North Korea, for example).  But kids continue to die in Africa from malaria because of the ban of that nasty chemical DDT.

Plastic, Chemicals, Internal Combustion Engines, Glass and Steel save Lives

But there are still some of us that want to get away from it all.  Who eschew this modern world.  They want to get back to a simpler time.  And some do.  In retirement.  Move out to the country.  Away from the big noisy cities.  And away from those big city hospitals.

Not my dad, though.  Good for him, too.  For he had a couple of heart of attacks.  The paramedics were at the house in about 7 minutes.  They had him in the hospital emergency room about 20 minutes later.  They saved his life.  Twice.  With all those things of the modern world.  Plastic.  Chemicals.  The internal combustion engine.  And a glass and steel building in a concrete jungle.

George Washington lived in that environmental paradise some pine for.  He died in 1799.  From what started out as a sore throat.  Washington was the Father of our Country.  The truly indispensible one.  The most powerful man in America.  He could have been king.  It was there for the taking.  He was that loved.  But that didn’t matter in 1799.  In that quaint time, a sore throat could kill.

The Miserable Enjoy Smelling Ass and Armpit?

In our modern world, we use daily showers, deodorant, perfume, cologne and even bidets.  It has become a pleasant smelling world.  And anyone who has sat on a 14-hour flight in coach can really appreciate how nice that is.

I like my concrete jungle.  It’s nice to know that falling asleep with a body part outside a mosquito net won’t kill me.  And if I get sick, it’s comforting to know that I can receive emergency medical treatment within 7 minutes. 

I don’t think those who want to turn the hands of time back fully understand how disgusting and dangerous those times really were.  Or they’re just miserable and hate life.  And they can only find comfort in making everyone as miserable as they are.  Either that or they just enjoy smelling ass and armpit.


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