“Nature abhors a vacuum!” you’ve heard people say.  In fact, your grandparents probably heard people say this too, and their grandparents before them...it’s been said for over 100 years!  But what does this really mean? 

First, to ‘abhor’ something is to dislike it very much, so nature does not like vacuums!  Second, the type of vacuum we are talking about is not just the kind you find in your house for cleaning floors.  When we speak of a vacuum in this way, we are talking about a space devoid of all matter.  That means the vacuum is a space where there is literally no (or almost no) atoms—not even air!  (Remember, air is made up of molecules of oxygen, nitrogen, carbon dioxide and others.  In a vacuum, there are none of these molecules either, so there is no air.)

It is almost impossible to remove ALL matter from any area, even in outer space, which is as close to a true vacuum as can be, having an average of only a few atoms per cubic meter, according to Takadoro in a 1968 paper in the Publications of the Astronomical Society of Japan.  On Earth producing a vacuum is even more difficult, with the best vacuum chambers achieving about 100 particles per cubic centimeter, according to Gabrielse in a 1990 paper published in Physical Review Letters.  Compare this to air at atmospheric pressure, which contains 3.369 X 1025 molecules per cubic meter (that’s essentially a 3 with 26 zeros behind it)!

Why is it so difficult to produce a vacuum?  Because matter likes to keep itself evenly spread out; so if a space with less matter is created, the matter in the surrounding areas wants to rush in and fill that space.  This is how your vacuum cleaner works:  there is a fan inside that creates a mild vacuum (enough to reduce the air pressure by about 20% according to Jeff Campbell in Speed Cleaning), which causes the dirt and dust to get sucked into the vacuum cleaner to replace the air particles removed by the fan.  (For more detailed information on how vacuum cleaners work, visit howstuffworks.com/vacuum-cleaner)

Although it is quite difficult to make a very strong vacuum, with only a few hundred molecules per cubic centimeter, it is not so difficult to make a partial vacuum.  While there is still a lot of matter left in a partial vacuum, the reduction in matter is enough to create some pretty interesting effects.

For instance, if we take an empty plastic water bottle and leave it in the sun with its cap off, the air inside the bottle will heat up.  This means the air molecules will be further apart, and some will leave the bottle.  If we then put the cap back on the bottle, and put the bottle in the freezer for five minutes, the air will cool down and the molecules will move closer together.  This forms a partial vacuum, because there will be fewer molecules per cubic centimeter in the bottle than on the outside of the bottle (remember, some of them left the bottle when it heated up in the sun).  Because of this partial vacuum, the sides of the bottle will cave in! 

Go ahead and try this!  Just remember to put the cap back on the bottle before putting it in the freezer!

We can also use partial vacuums like this to do an age-old trick—pulling a hard-boiled egg into a bottle!

TRY IT!!

Here’s what you’ll need:

1.       A hard-boiled egg, peeled (extra large eggs work well).

2.       A glass bottle with a mouth just a little narrower than the egg.  A 1 liter Erlenmeyer flask works very well.

3.       Strips of paper, about 6 inches long by 1 inch wide.

4.       Matches or a lighter

Here’s what to do:

1.       Carefully set one of the pieces of paper on fire, and drop it into your Erlenmeyer flask.

2.       Allow about three seconds to pass—count to three slowly.

3.       Place the egg on the mouth of the flask, narrow end down.  The egg may jump around a little.  This is because hot gasses are still escaping from the flask. 

4.       You should see the flame on the paper go out; then watch as the egg is pulled into the bottle!

Why does this happen?  It happens for the same reason that the water bottle’s sides cave in when put in the freezer.  The flame heats up the air in the flask, allowing some of the molecules to escape (making the egg jump around on top of the flask at first).  When the flame goes out the air starts to cool, and the air molecules get closer together, forming a partial vacuum.  This partial vacuum pulls the egg into the bottle!


So, what else could you try this with?  How about balloons?  Jell-O?  Get creative!  But always be sure to write down everything you do, and all your observations!

References for further reading:

Tadokoro, M. (1968). "A Study of the Local Group by Use of the Virial Theorem". Publications of the Astronomical Society of Japan 20: 230.

Gabrielse, G., et al. (1990). "Thousandfold Improvement in Measured Antiproton Mass". Phys. Rev. Lett. 65 (11): 1317.

Campbell, Jeff (2005). Speed cleaning. p. 97.

You’ve probably played with a beach ball at the pool or the beach, and you know that if the ball hits the water, it will float.  You may have gone on a hike and seen sticks and leaves floating in rivers and puddles.  The beach ball, the leaves and the sticks all have one thing in common—they all float on the water. 

Of course not all things will float on water such as coins or car keys!  Why do the leaves and sticks float, while the keys sink?  To understand why some things float on water, we have to understand buoyancy.

Buoyancy (pronounced BOY-an-see) is the upward push of water (or other liquid) on an object placed in it.  If the water can push upward on the object with enough force, then the object will float.  This means that the objects which float in water push down on the water less than the water is able to push back. 

Think of it like this:  if we get a big, empty cardboard box, and ask a small person to hold it over their head, they should not have any difficulty holding the box up.  After all, a cardboard box is not too heavy, especially if there is nothing in it.

But now what will happen if we fill the box with heavy books?  Now that one person cannot hold the box over their head. 

Water is a little like the person we got to hold the box.  The box with nothing in it is like the sticks or the beach ball:  there is not much matter (‘stuff’) in it, so it is easy for the water to hold up.  This is why they float.  The keys however have a lot more matter in them, so they are like the box full of books.  The water under the keys cannot hold up that much ‘stuff’, so they sink. 

So how can we know if something has too much matter in it for it to float on water?  The amount of matter in an object is called its mass, and the amount of mass something has per unit of volume (size) is called its density.  So, if something is denser than the water (that is, it has more mass per unit volume than the water does), it will sink.  If it is less dense than water, it will float. 

Here’s an example.  Let’s say we have one gallon of pure water.  This water has a weight of 8.3 pounds.  So we say that the density of the water is 8.3 pounds per gallon.  Now, let’s say we have one pint of rubbing alcohol, like the kind you buy at the drug store.  The volume of the water and the rubbing alcohol are the same, but this much alcohol only weighs 6.6 pounds.  So the alcohol is less dense than the water.  On the other hand, if we had a gallon of ethylene glycol (a major ingredient in antifreeze) it would weigh 9.2 pounds.  So the ethylene glycol is denser than water.  If we place one tablespoon of each, ethylene glycol, rubbing alcohol, and water in a test tube very carefully, they will stay separated: the rubbing alcohol will float on the water, and the ethylene glycol will sink. 

Clearly, if something floats on water that means it is less dense than the water.  We could also say the water is denser than the object.  But does all water have the same density?  As it turns out, the answer is no!  Seawater (that is, water with a lot of salt in it) is denser than pure water.  This is because when we dissolve salt in water, this water now has more matter—more ‘stuff’—in it, but the volume is the same.  This means that if something does not float in pure water, it may float in water that has a lot of salt dissolved in it—if we can add enough salt that we raise the density of the water above that of the object. 

TRY IT!!

Here’s what you’ll need:

1.       Two raw eggs

2.       Two large, clear drinking glasses

3.       Water from a sink

4.       About 1 cup of salt


Here’s what you need to do:

1.       Fill both of your glasses about half full with the water from the sink.

2.       Stir one cup of salt into one of the glasses of water.  Stir the water and salt for at least 2-3 minutes until as much salt dissolves as possible.  Don’t worry if not all the salt dissolves.

3.       Gently lower one egg into the glass with plain water, and the other egg into the glass with the salt water.  Observe what happens, and be sure to write down all your observations.

What happened to the egg in the plain water?  What about in the salt water?  Why did this happen? 

BE SURE TO WRITE DOWN EVERYTHING YOU DO AND EVERYTHING YOU OBSERVE IN YOUR NOTEBOOK!



References for further reading:

Buoyancy.  Wikipedia.  2014, Mar 17.  Retrieved 3-17-2014.  (http://en.wikipedia.org/wiki/Buoyancy)

Buoyancy.  HyperPhysics.   Retrieved 3-17-14 (http://hyperphysics.phy-astr.gsu.edu/hbase/pbuoy.html)

If there’s one thing you find everywhere, its soil!  Few things are quite so universal; all over the world soil takes part in our planting, building, cleaning, and playing.  Without it, none of the crops we use for food, clothing, or fuel could be grown.  Like so many universal things, it is very easy to take our soil for granted; it seems so simple, but soil is really very complex!

What we know as soil is really a mixture of many things:  minerals from the rock—or parent material—from which the soil is formed, organic materials from the organisms that live in the soil—such as plants and bacteria, water, and dissolved gasses—nitrogen, oxygen, and carbon dioxide.   Soil is formed when time and the elements (wind, weather, and living organisms) break down rock and mix in organic materials in different amounts to create the mixture of fine particles, sand, and stones we know generally as soil.

One of the most important characteristics of a particular soil is its texture (that is, how large or small the particles are which make up that soil).  The larger the size of the particles that make up the soil, the more coarse the soil will be.  Also, the smaller the particles that make up the soil, the finer and smoother the texture of the soil will be.  There are essentially three kinds of particles that can make up any soil: 

1.  Sand:  These are very large, coarse mineral particles.  Imagine the sand at the beach, or in a sandbox.  If you rub it between your hands, it is very rough and scratchy.  This is because the grains of sand are very big. Try to squeeze wet sand through your fingers, and it will just crumble.  This is how you can test if soil is made up of a lot of sand.

2.  Clay:  These are the smallest particles you can find in soil.  If you have ever played with modeling clay, you know it is very soft, smooth, and silky.  This is because the particles of the clay are so small—usually you cannot even see the individual particles!  Try to squeeze wet clay through your fingers, and it will form long, smooth ribbons.  This is how you can tell if a soil is made up of a lot of clay.

3.   Silt: These are particles with a medium size, between sand and clay.  Because they have a medium size, silt particles make a soil with a texture that is in between clay and sand.  If you squeeze wet silt through your fingers, it will make ribbons, but these ribbons will fall apart shortly after going through your fingers.

The reason soil texture is so important is because different soil textures hold water differently.  Water is very important for the plants that grow in the soil, so how well the soil holds the water will affect how well that soil is able to grow crops (and if the crops don’t grow well, there will be less food to go around!). 

Soil that is very coarse will let water in, but also lets the water run out very quickly.  This means the water will travel too deep for the plant roots, and will travel too fast for the plant to soak it up.  Very fine soil, like clay, does not let the water in very fast.  In fact the water will often sit on top of the soil, and just evaporate or run off without soaking in!  Plants growing in clay may not get the water they need from this soil either, because the water will not be able to get to the roots. 

Very good soil for growing plants should be a mixture of these soil textures:  enough sand to let water in, but enough clay to hold onto that water, and not let it flow away too quickly.  Soils with equal amounts of sand, silt and clay are called loam, and these are considered the best for growing plants. 

EXPERIMENT WITH DIFFERENT SOIL TYPES!!

Here’s what you’ll need:

1.    2-3 cups each of sandy and clay soil.  You can usually buy these at home improvement stores, or on the internet.  You could also find these soil types in the environment!  Just ask a local county extension agent or Natural Resource Conservation Service soil scientist where to look!

2.    2-3 cups of water

3.    A ½ cup measuring cup

4.    Clear plastic cups

5.    A nail or a pin

6.    A kitchen scale

7.    A sink that can be easily rinsed

HERE’S WHAT TO DO!

1.    Take two of your plastic cups, and poke a few holes in the bottom with your nail or pin.

2.    Put ½ of a cup of the sandy soil in one plastic cup, and ½ of a cup of the clay soil in the other cup.

3.    Place the cups, one at a time, on the scale, and record their weights.

4.    Pour ¼ of a cup of water over each of the cups of soil and place them in the sink.  Allow them to drain for 5 minutes.

5.    Weigh each of the cups again, and record the weights.  How much has each cup gained?  All this weight comes from the water.

6.    Take a look at each cup.  Can you see where the water is?  Where did the water go for the sand soil?  For the clay soil?  Write down what you see!

7.    Now take ¼ of a cup of each soil, and mix it in another plastic cup.  Be sure to poke some holes in the bottom of this cup too!

8.    Weigh the cup with your mixed soil.  Record the weight.

9.    Pour ¼ cup of water over this soil, and let it drain in the sink 5 minutes.

10.  Weigh this cup again, and record the weight.  How much extra weight does this soil have?

11.  Where is the water in this soil?  Is it sitting at the top, or did it move to the bottom?  Is the soil holding onto the water any better than the clay or the sand alone?

12.  Try mixing the soil in different amounts.  Each time you mix the different soils, write down how much of each one you mixed, and then pour ¼ cup of water over it.  Let it drain 5 minutes each time.  Be sure to weigh the soil before and after to see how much water the soil holds. 


What did you find out about how much water the soil will hold?  What was the best combination of sand and clay? 

Try planting seeds in the soil you have mixed.  Choose seeds that do not grow too large.  Remember to water the seeds every day, or whenever the soil feels dry.  Compare the growth of your seeds to the growth of the same kind of seeds in potting soil you can buy at the home improvement store. 

Be sure to WRITE DOWN ALL THE THINGS YOU DO (what types of seeds did you use, how many did you plant, and what type of potting soil did you try), AND ALL YOUR OBSERVATIONS (how many plants grew, how tall did they grow, how much time did it take for the first seedlings to appear)!


References for further reading:

1)       Soil.  Wikipedia.  2014, Mar 12.  Retrieved  3-12-2014.  (http://en.wikipedia.org/wiki/Soil)

2)       Hausenbuiller, R. L.  (1972).  Soil Science: Principles and Practices.  Dubuqe, IA: Wm. C. Brown Company Publishers.  ISBN: 0-697-05851-4.

Almost anywhere you go in the United States, you hear people talk about the glaciers and how they created the landscapes around us.  Geologists and historians explore the landscape, pointing out river basins, hills, and valleys, commenting on the role the glaciers’ played in their formation.   We read about them in books; pictures of great walls and rivers of ice unfurl their majesty across full-color pages.  These giants contain most of the fresh water on Earth (Brown, et al.), are present on every continent except Australia, and their gradual change in size is a great indicator of changes in global climates (Post and LaChapelle). 

But what is a glacier exactly, and how does one form?  How can something so large—and which does not appear to be moving at all—create such dynamic landscapes?

A glacier is body of dense ice formed from long-term accumulation of snow.  This snow builds up faster than it is able to melt or sublimate (evaporate back into the atmosphere without melting), and thus accumulates over many centuries, becoming heavier and heavier.  It becomes so heavy that it moves under its own weight, slowly sliding downhill under the force of gravity, or across a thin layer of water created by water from ice melting at its base.

As the glacier moves along the landscape, it pushes up rock from the terrain under it.  It does this when some of the water melts, flows into the small cracks in the rock below, and then freezes again.  When water freezes it expands (see the answer to “Why does ice float?”), and acts as a lever to pry up pieces of this rock, which then begin to move along with the glacier as it travels.  This is called “plucking”, because the rock was “plucked” from the bedrock.  Some pieces of rock may travel hundreds of miles! 

As glaciers continue to move, carrying their load of plucked rocks and boulders, they also scratch and scrape the landscape underneath, grinding and polishing the bedrock.  The result is called “rock flour”, and it is made up of tiny rock particles smaller in diameter than a human hair.  This is called “abrasion”, and is the other major way in which the glaciers shape and define our landscapes.  This abrasion also causes striations, or gouges in the landscape, along the path of the glacier, allowing geologists to map the progress of the glacier.

Through the plucking and abrasion of the bedrock below, the glaciers produce a variety of different landscape features.  The various hill formations include moraines, drumlins, and roche moutonnée.

Moraines:  Linear mounds of till, an assortment of rocks and boulders surrounded by fine rock flour.  These may appear at the front of the glacier (terminal or end moraines), or at the sides of the glacier (lateral moraines).

Drumlins:  Elongated hills made of glacial till, resembling the shape of an elongated bullet or a thin, rounded wedge.

Roche moutonnée (or “sheep back”):  A rock formation polished smooth, shallow slope on one side, and having a sharp cliff face on the other side.  These are formed when a glacier passes over a rock formation, polishing it as it moves up one side of the formation.  As the glacier tries to move down the other side of the formation, it plucks away rock, creating the sharp face. 

Glaciers also change landscapes by moving through valleys, rounding, widening, deepening, and smoothing their features.  Due to this polishing, a glacial valley will have pointed, triangular cliff faces from the sides of the adjacent mountains, called truncated spurs. 

The points at which glaciers form prior to flowing into a valley are three-sided bowl-shaped cirques, where the snow begins to accumulate to form the valley glacier.  Two or more glacial cirques may form side by side, forming a sharp arête in the middle.  If many cirques encircle a mountain, they form sharp peaks at the top of the mountain, called horns. 

As temperatures rise, and the glaciers begin to melt, they eventually start to recede.  The melting glacier will leave deposits of all the till and debris it has accumulated, leaving hills and mounds of sediments.  Hills and mounds that form as a glacier recedes are called kames, while elongated deposits are called eskers. 

TRY MAKING YOUR OWN GLACIER!*

*Procedures for this activity were provided by Ms. Betsy Watts from Hope, North Dakota.  Thank you to Ms. Watts!

While we don’t have thousands of years to wait for a glacier to form, we can simulate one using a plastic cup, some sand, and a few rocks.  We can simulate the landscape too, using a baking sheet and modeling clay!

Here’s what you’ll need:

1.       2-3 plastic cups

2.       Sand, about half a cup or so

3.       Pebbles of different sizes

4.       3-4 rocks, about 1 inch in diameter

5.       A baking sheet (one you don’t want to use again!)

6.       Enough modeling clay to cover the bottom of the baking sheet, preferably of a pale, muted color

7.       Water from any faucet

Here’s what you need to do:

Put some sand, pebbles, and a few rocks in the bottoms of your cups. Add enough water to just cover the rocks—a little more than one inch in the bottom of the cup.  Place these cups in the freezer overnight.

Meanwhile, press your clay into the bottom of your baking sheet.  This clay will become your glacial landscape.

After sufficient time for the water to freeze, remove your cups from the freezer, and cut the plastic away to release the ice and debris.  These are now your “glaciers”. 

                                                              

Place one of your glaciers, debris side down, onto the clay on one end of the baking sheet.  Apply gentle pressure with your hand, and slowly push the glacier IN A SINGLE DIRECTION along the clay.  You will see striations form in the clay from the debris, and you will push up ribbons of the clay along the front and sides of the glacier. 

When you get to the other end of the baking sheet, allow the glacier to remain there and begin to melt.  Repeat the process with the other glaciers you made.  Because no two glaciers are exactly alike, you will make different formations each time. 

After all your glaciers have melted, take a look at your new landscape and try to identify some of the formations.  Where are the moraines?  Drumlins?  Look at the difference between where your glacier passed, and where it melted.  Where are there more deposits—that is, where did your rocks and pebbles end up?  REMEMBER TO WRITE DOWN ALL YOUR OBSERVATIONS IN A NOTEBOOK!



References for further research:

1)      Brown, Molly Elizabeth; Ouyang, Hua; Habib, Shahid; Shrestha, Basanta; Shrestha, Mandira; Panday, Prajjwal; Tzortziou, Maria; Policelli, Frederick; Artan, Guleid; Giriraj, Amarnath; Bajracharya, Sagar R.; Racoviteanu, Adina. "HIMALA: Climate Impacts on Glaciers, Snow, and Hydrology in the Himalayan Region". Mountain Research and Development. International Mountain Society. Retrieved 16 September 2011

2)      Post, Austin; LaChapelle, Edward R (2000). Glacier ice. Seattle, WA: University of Washington Press. ISBN 0-295-97910-0.

3)      Glacier.  Wikipedia.  2014, Feb 28.  Retrieved 3-2-2014.  (http://en.wikipedia.org/wiki/Glacier)


Licenses:

Wikipedia: Creative Commons Attribution-Share Alike 2.5 Unported license

Wikipedia: Creative Commons Attribution-Share Alike 3.0 Unported license

This week’s blog is for high schoolers (or anyone else taking a chemistry class)!  If you are in a chemistry class, or have ever taken a chemistry class, you know it’s important to understand how to balance a chemical equation.  A chemical equation is how we can describe the reaction between two atoms or molecules in a concise way (for more information on chemical reactions, click here).  On the left side of a chemical equation are the reactants, or the substances we start with before the reaction.  On the right side of the equation are the products, the substances that are created in the reaction.  For instance, the reaction between hydrogen and oxygen to create water would be written like this:

We would read this equation as “hydrogen reacts with oxygen to produce water”.  You will also notice in this equation that there is a number two in front of the hydrogen, and a number two in front of the water (H2O).  These numbers are called coefficients, and they are there to show us that for this reaction to take place, two molecules of H2 must react with one molecule of O2 to form two molecules of water. 

You may ask, “Why should we need these coefficients?  Why not just write it out as simply as possible?”   Well, if we write out what really happens in the reaction, our equation would look like this:

Yes, this is very simple, but there is a problem with it.  Hydrogen and oxygen (as well as nitrogen and halogens like chlorine and fluorine) don’t appear as single atoms in nature, they appear as molecules with two atoms each. 

In order to understand what is really happening during the reaction, we must write our reactants as they really appear.  This means writing their formulas as H2 and O2 (because one molecule has two atoms of hydrogen or two atoms of oxygen).  Now if we try to write our chemical formula using these correct molecular formulas, we end up with this:

But now we have another problem...now the equation does not balance. 

What we mean by this is that the number and type of atoms from the reactants on the left side of the equation do not match the products on the right side.  We know that in the real world this cannot be the case, because the law of conservation of mass states that atoms are neither created nor destroyed in any chemical reaction. 

Take a look at our last equation again.  On the left there are two hydrogen atoms and on the right there are two oxygen atoms.  On the right there are two hydrogen atoms (this is good), but only one oxygen atom.  This implies that one of the oxygen atoms just disappeared, and we know this cannot be!  This means the equation is unbalanced.  To fix this, we need to add our coefficients.  Let’s start out by bringing back the missing oxygen atom.  We do this by putting the coefficient 2 in front of water.  This means now there are two molecules of water, each of which has one oxygen atom, for a total of two oxygen atoms.

But now on the right side there are four hydrogen atoms:  each molecule of water has two hydrogen atoms, and there are two molecules, for a total of four hydrogen atoms.  We can fix this by putting the coefficient 2 in front of the hydrogen on the left side, giving us a total of four hydrogen atoms on the left side also.

Now our equation is balanced! 

Let’s try another synthesis reaction—the reaction between nitrogen and hydrogen to form ammonia:

Let’s start by balancing the nitrogen.  There are two nitrogen atoms on the left, and one on the right.  We can make these balance by adding the coefficient 2 in front of the ammonia on the right side:

Now the hydrogen must be balanced; there are two hydrogen atoms on the left, and six on the right.  We can make this balance by adding the coefficient 3 in front of the hydrogen on the left side:

This equation is now balanced!

Now let’s try another, more challenging reaction, such as the displacement reaction between aluminum and hydrochloric acid (remember, a displacement reaction happens when atoms of one element displace the atoms of another element in a molecule).  In this reaction, aluminum displaces hydrogen as the bonding partner with chloride:

Clearly this equation is not balanced.  There is one aluminum atom on each side, so this is OK so far.  There is only one hydrogen atom on the left but there are two on the right, and there is only one chloride atom on the left and there are three on the right.  We need to find a way to balance the hydrogen and chloride atoms. 

First, let’s look at the chloride atoms, since this is the largest imbalance between the two sides.  To fix this imbalance, we would need to put a coefficient 3 in front of the hydrochloric acid:

Now, look at the hydrogen atoms.  There are now three on the left and two on the right.  To make this balance we need to find the least common multiple of two and three, which is 6.  This means we need 6 hydrogen atoms on either side of the equation.  This is how our coefficients will look:

Our aluminum is still OK, but now we need to look at the chloride again.  We have six atoms of chloride on the left side, and three on the right.  We can fix this by adding the coefficient 2 in front of the aluminum chloride molecule:

Now our hydrogen atoms balance, and our chloride atoms balance, but our aluminum atoms don’t!  Finally, these also need to balance, so we need two on the left side; we simply add the coefficient 2 in front of the aluminum atoms on the left:

Now all atoms in the equation balance.  This equation required a little more jostling back-and-forth, but don’t let that worry you!  Just keep going back and forth until all the atoms balance, starting with the atoms that are the most imbalanced, and working toward the ones that are the least imbalanced.  This is a little like hitting a baseball, or riding a bike—it takes a little practice to get really good at it!

Let’s try one more, the combustion of propane in oxygen from the air:

Because the oxygen appears in both of the products of the reaction, I’m going to leave oxygen for last.  The greatest imbalance is for hydrogen, with eight atoms on the left, and two on the right.  To make the hydrogen balance, we need to insert the coefficient 4 in front of the water:

Next let’s look at the carbon atoms.  There are three on the left and one on the right, so we need to add the coefficient three in front of the carbon dioxide:

The hydrogen and carbon atoms now balance, what about oxygen?  There are ten oxygen atoms on the right side, so we must add the coefficient 5 in front of the oxygen.

Now all atoms balance on both sides of the equation.

NOTE:  The most important step of balancing a chemical equation is simply making sure that your reactants and products are written correctly.  If they are not, the equation will never balance and you will spend many fruitless hours struggling.  If you are having a lot of trouble getting a reaction to balance, this is usually a good place to start looking for answers! 

TRY THESE!!

Fill in the blanks with the proper coefficients. 

1)      _Al + _O2 = _Al2O3

2)      _Na + _H2O = _NaOH + _H2

3)      _C2H4 + _O2 = _CO2 +_H2

4)      _Si2H6 + _O2 = _SiO2 + _H2O

5)      _CH3OH + _O2  = _CO2 + _H2O

ONLY WHEN YOU ARE DONE....go ahead and scroll down!


 















Answers:

1)      4, 3, 2

2)      2, 2, 2, 1

3)      1, 2, 2, 2

4)      2, 7, 4, 6

5)      2, 3, 2, 4