Balancing Chemical Reaction Equations

Being able to balance chemical equations is a very important skill for students of chemistry.

The act of balancing an equation will be confined to making sure that atoms are conserved, that is, having the same number of each type of atom on each side of the equation.

Atoms are conserved means whatever atoms are on the reactant side(left) must be on the product side(right) and there must be the same amount of each atom on both side. This is because of the law of conservation of matter which states that matter can neither be created nor destroyed in any physical or chemical process.

The physical state of reactants and products indicated when writing chemical equations are indicated like this: Solid=(s), Liquid=(l), Gas=(g), Aqueous=(aq).


Steps of Balancing a Chemical Equation
1. Identify each element found in the equation. The number of atoms of each type of atom must be the same on each side of the equation once it has been balanced.
2. The net charge must be the same on each side of the equation once it has been balanced.
3. If possible, start with an element found in one compound on each side of the equation. Change the coefficients so that the number of atoms of the element is the same on each side of the equation.
(PS: Change the coefficients, not the subscripts in the formulas)
4. Once you have balanced one element, do the same thing with another element. Proceed until all elements have been balanced.
5. Check your work to make certain the charge on both sides of the equation is also balanced.


The following example shows the balancing process.

EXAMPLE:
? CH4 + ? O2 → ? CO2 + ? H2O
Identify the elements in the equation: C, H, O
Identify the net charge: no net charge, which makes this one easy.
1. H is found in CH4 and H2O, so it's a good starting element.
2. We have 4 H in CH4 and only 2 H in H2O, so we need to double the coeffient of H2O to balance H.
CH4 + ? O2 → ? CO2 + 2 H2O
3. Looking at carbon, CH4 and CO2 must have the same coefficient.
CH4 + ? O2 → 1 CO2 + 2 H2O
4. Determine the O coefficient. We need to double the O2 coefficient in order to get 4 O seen on the product side of the reaction.
CH4 + 2 O2 → 1 CO2 + 2 H2O
5. Check your work. We don't need to write the coefficient if it is one. So the balanced equation would be written:
CH4 + 2 O2 → CO2 + 2 H2O

Then, you can do some exercises to check whether you understand or not. These will be a little bit difficult than that one.

1.) S+KOH → K2S+K2SO3+H2O
→3S+KOH → 2K2S+K2SO3+H2O

Final answer:
3S+6KOH = 2K2S+K2SO3+3H2O

2.) Mg+HNO
3 → Mg(NO3)2+NH4NO3+H2O

Final answer:
4Mg+10HNO
3 → 4Mg(NO3)2+NH4NO3+3H2O
Do you get the right answers?
If you still feel confused, you can do the exercise on the textbook on Page 110-112 and you can check the answers on the textbook after you finish them as well.