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# How do you balance a chemical equation?

i have a test tomorow and i understand everything but this. help? kthnx!

Wait until you get moles and weight and all that. It is fun though! But like the other guy said, go until all your elements on the right side = the left. IT gets really really really really easy once you get it. I want to learn organic chemistry. Firstly, understand the fundamental law of balancing which determines the basic procedure you MUST follow:

1. The number of atoms for each element (indicated by the coefficients and the small index number) must be the same

Coefficients signify that a number of 'molecules' are present. when balancing. For instance: 2CO is two molecules of Carbon Monoxide which is then 2 atoms of carbon and 2 atoms of oxygen which CO2 (small two. ;)) is one atom of carbon and two atoms of oxygen which is ONE molecule.

To finish up, pay particular attention to the difference between coefficients and indexes and regardless of how complicated the balancing may get the process remains the same and it may be solved!

Remember to draw that line which separates the reactants and the products! ---------------> You can easily lose a mark for this. Also remember that ONLY elements may be included. So, don't include energy and volumes etc. These are NOT part of the equation.

Hope this helps. In a chemical reaction, the quantity of each element does not change. Thus, each side of the equation must represent the same quantity of any particular element. Also in case of net ionic reactions the same charge must be present on both sides of the equation. Then, and only then, the equation is balanced. Given an unbalanced equation, one may balance it by changing the scalar number for each molecular formula.

Simple chemical equations can be balanced by inspection, that is, by trial and error. Generally, it is best to balance the most complicated molecule first. Hydrogen and oxygen are usually balanced last.

Ex #1. Na + O2 в†’ Na2O

In order for this equation to be balanced, there must be an equal amount of Na on the left hand side as on the right hand side. As it stands now,

there is 1 Na on the left but 2 Na's on the right. This problem is solved by putting a 2 in front of the Na on the left hand side:

2Na + O2 в†’ Na2O

In this equation there are 2 Na atoms on the left and 2 Na atoms on the right. In the next step the oxygen atoms are balanced as well. On the left hand side there are 2 O atoms and the right hand side only has one. This is still an unbalanced equation. To fix this a 2 is added in front of the Na2O on the right hand side. Now the equation reads:

2Na + O2 в†’ 2Na2O

Notice that the 2 on the right hand side is "distributed" to both the Na2 and the O. Currently the left hand side of the equation has 2 Na atoms and 2 O atoms. The right hand side has 4 Na's total and 2 O's. Again, this is a problem, there must be an equal amount of each chemical on both sides. To fix this 2 more Na's are added on the left side. The equation will now look like this:

4Na + O2 в†’ 2Na2O

This equation is a balanced equation because there is an equal number of atoms of each element on the left and right hand sides of the equation.

Ex #2. P4 + O2 в†’ P4O10

This equation is not balanced because there is an unequal amount of O's on both sides of the equation. The left hand side has 4 P's and the right hand side has 4 P's. So the P atoms are balanced. The left hand side has 2 O's and the right hand side has 10 O's. To fix this unbalanced equation a 5 in front of the O2 on the left hand side is added to make 10 O's on both sides resulting in

P4 + 5O2 в†’ P4O10

The equation is now balanced because there is an equal amount of substances on the left and the right hand side of the equation.

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