Now, Let's Go Further!

For Teaching Purposes, Let's Consider The Following:

If I had 1 gram of hydrogen and 2 grams of oxygen how many grams of water would I get?
Remember the chemical equation for water is 2H2 + O2 → 2H20

Step One: You Must Find The Limiting Reagent

now that we know how to find the limiting reagent, let's solve for it as our first step.

Step One: Find the molar mass of H2 and O2:

 H * 2 = 1 * 2 = 2 grams/mole                          O * 2 = 16 * 2 = 32 grams/mole

Step Two: Divide each reagents number of grams by its molar mass

 1 gram                    2 grams : as given in the equation, you have 1 gram of hydrogen and 2 grams of oxygen
 2 grams/mole         32 grams/mole : molar mass of 2 hydrogen (1) and 2 oxygen (16)
0.5 moles                0.6 moles

O2 is the limiting reagent

Step Two: Compare the Molar Ratio of the Limiting Reagent to the Product

multiply the limiting reagent in moles by the quotient of the coefficient of the product and of the limiting reagent

0.6 moles * (2 moles of H2O /1 mole of O2) = 1.2 moles

Step Three: Convert Moles Back Into Grams

multiply your result by the molar mass of the product

1.2 moles * 18 grams/mole = 21.6 grams