Write and balance the equation for the formula of aluminum oxide from its elemental composition.

Question

also, determine the limiting reactant give 1.0 g of aluminum and 1.0 g of oxygen

Answer 1

Aluminum oxide has the formula Al₂O₃.

 

4Al + 3O₂ ==> 2Al₂O₃  <-- balanced equation

 

In a previous question that you asked, I went through the procedure for calculating limiting reactant.  Here, I will actually do the calculations so you can see how it is done.

 

moles of Al present = 1.0 g Al x 1 mole Al/27 g = 0.037 moles Al present

moles of O2 present = 1.0 g O2 x 1 mole/32 g = 0.031 moles O2 present

You might think that since there is less O2 than Al, that O2 is limiting, BUT... look at the balanced equation where you need 4 moles Al for every 3 moles of O2, so Al is actually the limiting reactant. (If you don't see how this is the case, just divide the moles of each reactant by the coefficient in the equation, and the smallest number is the limiting reactant).