How do you balance an equation?

Answer 1

Hi Balancing an equation is quite easy. E.G. H2 + O2 ---> H2O To balance this equation you would draw a table Left Side ----Right Side H2----------------H2O O2 So you have 2 hydrogens and 2 oxygens on the left hand side of the equation and 2 hydrogens and 1 oxygens on the right hand side so you have need times the H2O by two making it 2H2O . Left Side ---Right Side H2 -------------2H2O O2 You know have the same amount on the left hand side but now have 4 hydrogens and 2 oxygens, so now you can times the hydrogens on the left hand side by 2 making the equation equal. Left Side----Right Side 2H2 ------------2H2O O2 You now have 4 hydrogens and 2 oxygens on the left side and 4 hydrogens and 2 oxygens on the right side, so it is balanced. Draw this table whenever you need to balance an equation.

Answer 2

Well you need to know the reacting species and a knowledge of chemistry.

The aim of balancing an equation is to get the same amount of each element on both sides. You can do this by changing the amount of any of the reactants or products, but you cannot change the chemical formulae of the chemicals.

To balance an equation, choose an element to work with first. This should preferrably be an element that is present in only one reactant and one product to make things simpler. Then, change the amount of one of the chemicals to make the number of atoms of that element the same on each side.

Repeat this for the other elements and eventually you should end up with the same amount of each element on each side of the equation.

Of course, there are slightly different ways of dealing with each type of reaction's equation, so here are a few examples: -

Example 1:

magnesium + hydrochloric acid => magnesium chloride + hydrogen

Mg + HCl => MgCl2 + H2

Looking at the amount of Mg (magnesium) first, we notice that this is already the same on both sides. Next, we may choose to look at the amount of H (hydrogen). There are two on the right but only one on the left, so we must multiply the amount of HCl by 2 to gain the necessary amount of hydrogen atoms. This also means we now have one more Cl (chlorine) atom on the left, and this matches the 2 on the right. So the balanced equation is

Mg + 2HCl => MgCl2 + H2

Example 2:

sodium carbonate + nitric acid => sodium nitrate + carbon dioxide + water

Na2CO3 + HNO3 => NaNO3 + CO2 + H2O

Checking the amount of Na first, we find that there are 2 on the left but only one on the right. Therefore we increase the amount of NaNO3 to 2. However, doing this now means we have an imbalance of N (or more specifically the NO3 groupbetween the acid and the sodium nitrate). This means we need to add another HNO3, and in doing this we have also added the extra H what was needed. The balanced equation looks like this:

Na2CO3 + 2HNO3 => 2NaNO3 + CO2 +H2O

Example 3:

propane + oxygen => carbon dioxide + water

C3H8 + O2 => CO2 + H2O

In this equation, the amounts of oxygen can get a little confusing, so we will oxygen until last. The amount of C on the left is 3 times that on the right, so we need to have 3 lots of CO2 to give the same amount of carbon. There are 8 Hatoms on the left and 2 on the right, so the amount on the left is 4 times bigger. This means we need to multiple the amount of H2O on the right by 4. So far the equation looks like this:

C3H8 + O2 => 3CO2 + 4H2O

But we still need to balance the amount of O atoms. There are 3 CO2 molecules with 2 oxygen atoms per molecule, so the number of oxygen atoms present in all of the 3CO2 is 6. There are also 4 H2O molecules with one oxygen atom each, so the total number of oxygen atoms in these is 4. This means that the total number of oxygen atoms on the right is 10. On the left, O2 is the only molecule containing oxygen, but it has 2 per molecule. We want 10 oxygen atoms rather than 2, so we multiply the amount of O2 molecules by 5. Our equation is now balanced and looks like this:

C3H8 + 5O2 => 3CO2 + 4H2O