How many moles of H2SO4 are needed to completely react with 15.0 mole of Al?
2Al + 3H2SO4 → Al2(SO4)3 + 3H2

The answer to your question is 22.5 moles of H₂SO₄

Explanation:

Data

moles of H₂SO₄ = ?

moles of Al = 15

Balanced chemical reaction

                2Al + 3H₂SO₄  ⇒  Al₂(SO₄)₃  +  3H₂

To solve this problem use proportions and cross multiplication. Use the coefficients of the balanced chemical reaction.

                2 moles of Al 3 moles of H₂SO₄

               15 moles of Al  x

                                    x = (15 x 3) / 2

                                    x = 45/2

                                   x = 22.5 moles of H₂SO₄

-Conclusion

22.5 moles of H₂SO₄ react completely with 15 moles of Al.