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Equations must be balanced because:
never by changing formula subscripts
Write the balanced equation for each of the following:
a way to represent chemical reactions on paper.
There will be a formal test before Lab Day. You will be asked to demonstrate that you can balance equations by inspection. Your paper periodic table and a "hand-held" calculator may be used during the test, but nothing else.
Atoms can be neither created nor destroyed in an ordinary chemical reaction, so there must be the same number of atoms on both sides of the equation.
These numbers are found in a chemical equation:
The small numbers to the lower right of chemical symbols. Subscripts represent the number of atoms of each element in the molecule.
The large numbers in front of chemical formulas. Coefficients represent the number of molecules of the substance in the reaction.
The order in which the following steps are performed is important.
While shortcuts are possible, following these steps in order is the best way to be sure you are correct.
Balancing Equations By Inspection
1. Check for Diatomic Molecules - H2 - N2 - O2 - F2 - Cl2 - Br2 - I2
If these elements appear by themselves in an equation,
they must be written with the subscript 2
2. Balance Metals3. Balance Nonmetals4. Balance Oxygen5. Balance Hydrogen6. Recount All Atoms
Balance equations by changing coefficients
This is a picture of Matt Miles
If the atoms are not balanced at this point, there is a problem somewhere. Work your way back up the steps, from bottom to top, until you find the problem, and correct it.
7. If every coefficient will reduce, rewrite in the simplest whole-number ratio.
An equation is not properly balanced if the coefficients are not written in their lowest whole-number ratio.
Practice Problems:
sodium oxide + water
iron (III) oxide
glucose + oxygen
iron (II) chloride + hydrogen sulfide
