 # Topic: Reaction Stoichiometry

## Summary

Reaction Stoichiometry (which is sometimes shortened to just Stoichiometry, even though there are other types of Stoichiometry) is a technique in Chemistry used to calculate the relative proportions in which Chemical Elements form chemical compounds or in which chemical stabstances react in chemical reacations.

##### Example

Here's an example reaction stoichiometry calculation.

``````
2H2 + O2 → 2H2O
``````

(Note, you need to understand the notation for the Chemical Elements to understand this example.)

###### Symbols in Example

In the above equation `H2` is how we typically find Hydrogen, such as hydrogen gas. (Hydrogen atoms often bind together in pairs.)

Also in the above equation `O2` is how we typically find Oxygen, such as the oxygen we breath. (Oxygen atoms often bind together in pairs.)

And `H2O` is Water.

###### Understanding the Example

So, this equation says you need to two molecules of Hydrogen (`H2`) for every one molecule of Oxygen (`O2`) and that will create 2 molecules of Water (`H2O`).

But it is the ratios that matter here. So, this also says that with 4 `H2` reacted with 2 `O2` gives us 4 `H2O` molecules.

And says that 6 `H2` reacted with 3 `O2` gives us 6 `H2O` molecules.

And also says that 8 `H2` reacted with 4 `O2` gives us 8 `H2O` molecules.

##### Moles

The reason equations like that are important is because we can use this information to figure out exactly how many Grams or Litres of a substance to react together, and how much of the resul we are going to get. And that is important!

-- Mirza Charles Iliya Krempeaux