If you wish to produce 100g of Iron Oxide, how many grams of Iron will you need?
You can do this two ways. The long way is to use stoichiometry. Here is a worked example.
http://www.jiskha.com/science/chemistry/stoichiometry.html
A shorter way is to use a chemical factor which isn't taught anymore that I know of. A chemical factor is the ratio of molar masses.
Fe ==> Fe2O3
100 g Fe x (molar mass Fe2O3/2*atomic mass Fe) = ??
To determine the grams of Iron needed to produce 100g of Iron Oxide, we need to know the molar mass of Iron Oxide and the ratio of Iron to Iron Oxide in the chemical formula.
Step 1: Find the molar mass of Iron Oxide.
Iron Oxide has a chemical formula of Fe₂O₃. To calculate the molar mass, we need to know the molar mass of each element in the formula.
The molar mass of Iron (Fe) is approximately 55.85 g/mol.
The molar mass of Oxygen (O) is approximately 16.00 g/mol.
To find the molar mass of Iron Oxide (Fe₂O₃), we multiply the molar mass of Iron by 2 (since there are 2 Iron atoms) and the molar mass of Oxygen by 3 (since there are 3 Oxygen atoms), and then add the two results together.
Molar mass of Iron Oxide (Fe₂O₃) = (2 * 55.85) + (3 * 16.00) g/mol
Step 2: Calculate the ratio of Iron to Iron Oxide.
From the chemical formula, we can see that there are 2 Iron atoms for every 1 molecule of Iron Oxide (Fe₂O₃).
Step 3: Calculate the grams of Iron needed.
To calculate the grams of Iron needed to produce 100g of Iron Oxide, we can use the following formula:
Grams of Iron = (Molar mass of Iron * 100) / Molar mass of Iron Oxide
Now, let's plug in the values we found:
Grams of Iron = (55.85 * 100) / [(2 * 55.85) + (3 * 16.00)]
By evaluating the above expression, you can determine the number of grams of Iron needed to produce 100g of Iron Oxide.