Question

For the reaction shown above, what is the chemical formula for the limiting reactant?

Answer 1

Chemical equation: 4Cr (s) +3O2 (g) ----> 2Cr2O3 (s)

The balanced equation above states that 4 moles of Cr react with 3 moles of O2 to produce 2 moles of Cr2O3

So, 1 mole of Cr needs 0.75 moles of O2.
If the mole ratio of Cr : O2 is not 1 : 1.333, then you have an excess of one reagent. The other reagent is the limiting reagent.

Set up a proportion to determine the amount of O2 needed.

The dots are to prevent yahoo answers from scrunching the letters and numbers to the left!!

.. (moles of Cr)