How many mole of Al2O3 are formed when 14.9g Al reacts with oxygen?
2 points

0.28moles  of Al₂O₃

Explanation:

Given parameters:

Mass of Al  = 14.9g

Unknown:

Number of moles  of Al₂O₃  = ?

Solution:

Let us write the reaction equation first;

              4Al   +   3O₂     →   2Al₂O₃

Now that we have obtained the balanced equation, we work from the known to the unknown. The known is the mass of Al.

Find the number of moles in this mass;

       Number of moles  =  

         Molar mass of Al  = 27g/mol

  Number of moles  =    = 0.55moles

From the balanced reaction equation;

           4 moles of Al will produce 2 moles of Al₂O₃

         0.55 moles of Al will produce    = 0.28moles  of Al₂O₃