LESSON ON STOICHIOMETRY
STOICHIOMETRY
The quantitative relationship between constituents in a chemical substance
It is used to balance chemical equations, calculate masses, moles and find the molar ratio between chemical reactions.
Ex: The following unbalanced equation is shown below. Balance the following equation.
Fe+O2= Fe2O3
The firsThe first step is to balance everything in the the equation. there are 2 oxygen atoms on the left side and 3 oxgen atoms on the right side. To make both sides equal 6, place a 3 before O2 on the left side and a 2 in front of the Fe on the right side. Both oxygen atoms are balanced. But iron is unbalanced, so place a 4 in front of Fe on the left side to balance it. So your new balanced equation is
4Fe+3O2=2Fe2O3
Here's an example on how to convert a mole to mole problem.
How many moles of H2 are used when 2.00 moles of oxygen is used?
To set up the problem, you first balance the equation.
2H2+O2=2H2O.
Next you write the given equation 2.00 moles. Then you multiply the given by the number of moles you are trying to find over the number of moles of your given.
2.00 moles of O2 x 2 moles of H2/ 1 mole of oxygen
When you multiply 2x2 you get 4 moles of H2.
Heres an example of a mass to mole problem.
The quantitative relationship between constituents in a chemical substance
It is used to balance chemical equations, calculate masses, moles and find the molar ratio between chemical reactions.
Ex: The following unbalanced equation is shown below. Balance the following equation.
Fe+O2= Fe2O3
The firsThe first step is to balance everything in the the equation. there are 2 oxygen atoms on the left side and 3 oxgen atoms on the right side. To make both sides equal 6, place a 3 before O2 on the left side and a 2 in front of the Fe on the right side. Both oxygen atoms are balanced. But iron is unbalanced, so place a 4 in front of Fe on the left side to balance it. So your new balanced equation is
4Fe+3O2=2Fe2O3
Here's an example on how to convert a mole to mole problem.
How many moles of H2 are used when 2.00 moles of oxygen is used?
To set up the problem, you first balance the equation.
2H2+O2=2H2O.
Next you write the given equation 2.00 moles. Then you multiply the given by the number of moles you are trying to find over the number of moles of your given.
2.00 moles of O2 x 2 moles of H2/ 1 mole of oxygen
When you multiply 2x2 you get 4 moles of H2.
Heres an example of a mass to mole problem.