Wednesday, February 23, 2011

Everything Being Equal Makes for Good Chemistry

Balancing... One Step At A Time

Being able to balance chemical equations is a very important skill for students of chemistry, making this one of our most popular chemistry tutorials. All chemical calculations require you to work with a balanced equation. Here we will show you a simple, easy way to balance all chemical equations you will meet at introductory level chemistry courses.

A chemical equation is balanced when the number of atoms of each type on each side of the equation is the same. Which means if you have 12 hydrogens on the left hand side of the equation, you must have 12 hydrogens on the right hand side, if there are 4 oxygens on the left, there must 4 oxygens on the right, and so on. This is because of the law of conservation of mass - you can't make or destroy atoms during a chemical reaction. But you can't just add atoms at random to each side, you have to work with the molecules of the reactants.

The key to balancing chemical equations is to apply the rules below.
If you already know the rules, then try these worked examples for revision practice.

Balancing chemical equations isn't difficult, once you know the way to do it. Start by finding out how many atoms of each type are on each side of the equation. Some teachers recommend making a little table listing the numbers of each atom for the left hand side and for the right hand side.Example 1

Unbalanced Equation:- C3H8 + O2 ---> H2O + CO2

There are three carbons on the left, but only one on the right.
There are eight hydrogens on the left but only two on the right.
There are two oxygens on the left but three on the right.

Next, look for an element which is in only one chemical on the left and in only one on the right of the equation. (But it is usually a good idea to leave hydrogen and oxygen until you've done the others first.)

To balance that element, multiply the chemical species on the side which doesn't have enough atoms of that type by the number required to bring it up to the same as the other side. The number is called the coefficient.
If you have to multiply by, say, 2 1/2, do so, THEN multiply EVERYTHING on each side of the equation by two to get rid of the half.
We don't like having halves in equations, as you can't get half a molecule.

Now look for the next element or species that is not balanced and do the same thing.

Repeat until you are forced to balance the hydrogen and oxygens.

Thanks to The Wright Stuff and Sky-Web,


  1. zachL/yellow

    I checked by work on balancing equations activity and got them all correct and this new entry to the blog reinforced what you have taught us in class.

    thank you

  2. Way to go Mrs V... that's 12,345,678,900 bonus points in the bonus box for you.

  3. Mr V, I need help on one of my templates. I am revising my beach species template and i am confused on what to do for recall help. Could you explain for me what to do there? thanks


  4. Tyler... "recall help" would be one or two good ways to remember how to identify your species...

    Think of "Red Red pointy Head" or "black Pirate Fingers" as examples.

    Hope this helps

  5. Mr. V, I read everything and I still don't understand what to do on the 4th equation on the Practice Blancing worksheet. Can you explain it?


  6. Well, if mr v. doesnt get to this in time, i can help you. I undersand it well. What i did was to start out with nothing in the blanks to see how they balanced out. With nothing there your C on the left side is 2 and on the right 4. H on the left would be 6 and on the right 2. O on the left would be 2 and on right 3. Then itried putting a 2 in the first space and it equaled C=4 on the left and H=12. on the first space on the right side of the arrow try 2(doesnt work) 3(doesnt work) 4! Then C=4 on both sides and you have one match.
    2C2H6+__O2 ---> 4CO2+__H2O
    C=4 C=4
    H=12 H=2
    O=2 O=3

    That will get you started to get the other two.
    Hope I couldhelp.

  7. Mr V. I have 2 questions.

    1. Why do crustaceans have to molt their shell?

    2. Why do crabs walk sideways?


  8. remember subscripts don't print in comments

    The most obvious error is that there are three chlorines on the left but only one on the right, and the chlorine is in a single chemical species on each side . Put a 3 in front of the NH4Cl on the right hand side.

    FeCl3 + NH4OH ---> Fe(OH)3 + 3NH4Cl

    The next most obvious unbalanced part is that there are now three NH4 groups on the right but only one on the left hand side. So put a 3 in front of the NH4OH on the left.

    FeCl3 + 3NH4OH ---> Fe(OH)3 + 3NH4Cl

    And if you count up the atoms on each side, you will see that this is now a balanced chemical equation.

  9. Who ever was trying to help Lindsey.. put three (3) in the bonus box.

  10. Crabs bodies grow but their shells don't grow along with them..

    Its the only their legs will bend. and they can fir into smaller holes and go in/out or left right easily without having to go in or out backward not seeing where they were going.

    That's a two pointer