Aluminum reacts with sulfuric acid, which is the acid in automobile
batteries. If 20.0 grams of Al is placed into a solution containing
115 grams of H2SO4, how many grams of hydrogen gas could be produced?

Hi teatea!!

Aluminum reacts with sulfuric acid to form aluminum sulfate and
hydrogen, and the balanced equation of this reaction is:
2 Al + 3 H2(SO4)  ---->  1 Al2(SO4)3 + 3 H2

The atomic mass of Al is 26.98g, then 1 mol of Al will weight 26.98g,
then we have:

20g /26.98 (g / mol)  = 0.7413 mol of Al.

On the other hand, the molecular mass of H2(SO4) is (2*1 + 32 + 4*16)g
= 98g.

0.7413 mol of Al need to react completely 3/2 * 0.7413 mol = 1.112 mol
of H2(SO4). This 1.112 mol of H2(SO4) are equivalent to 1.112 * 98g =
108.98g. This amount of H2(SO4) required for the complete reaction of
the 0.7413 mol of Al is less than the 115g of H2(SO4) then we have an
excess of H2(SO4) and the Al will react ompletely.

From 2 mol of Al we obtain 3 mol of H2, then from 0.7413 mol of Al we
will obtain 3/2 * 0.7413 = 1.112 mol of H2. Each mol of H2 weigths 2g,
then 1.112 mol of H2 weights 2*1.112 = 2.224 g 0of H2.

If 20.0 grams of Al is placed into a solution containing 115 grams of
H2(SO4), 2.224g  of H2 will be produced.


For more info about the equation of the reaction of the Aluminum with
sulfuric acid:
"Replacement Reactions":
http://www.sasked.gov.sk.ca/curr_content/parkland63/repguide.htm


I hope this helps; but if something here needs a clarification, please
post a request for it before rate the answer.

Regards.
livioflores-ga