Question

What is the limiting reactant when 4.5 moles of aluminum react with 6.7 moles of oxygen gas? Unbalanced equation: Al + O2 â ' Al2O3 Show, or explain, all of your work along with the final answer.

Answer 1

The things in place of the invalid character symbols were a ` and an a with an accent mark.

Answer 2

well if the reaction product is Al2O3, then 2 moles of aluminium will react with 3 moles of oxygen atoms

Answer 3

So the limiting reactant would be oxygen?

Answer 4

you've got 6.7 moles of oxygen gas, how many moles of oxygen atoms is that ?

Answer 5

3?

Answer 6

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how many oxygen atoms make up an oxygen molecule ?

Answer 7

Oh, two.

Answer 8

right, so however many moles of oxygen molecules you've got, there are twice as many moles of oxygen atoms

Answer 9

and for every 3 moles of oxygen atoms, you're going to need 2 moles of aluminium

Answer 10

The balanced reaction is:
\[2Al+\frac{ 3 }{ 2 }O _{2}=Al _{2}O _{3}\],
or, dividing by two:
\[Al+\frac{ 3 }{ 4 }O _{2}=\frac{ 1 }{ 2 }Al _{2}O _{3}\]
From the last equation, we have that 1 mole of Al, reacts, with 3/4 moles of O_2, in order to get 1/2 mole of Al_2O_3, so 4.5 moles of Al, are able to reacts only with 3/4*4.5=3.4 moles of O_2, in order to get 1/2*4.5=2.25 moles of Al_2O_3. FInally the excess of O_2, is 6.7-3.4=3.3 moles of O_2