Question

with the balanced equation Zn + 2HCl = H2 + ZnCl2 Calculate the moles of HCl needed to react completely with 8.25 moles of zinc.

Answer 1

For the reaction of Zn with HCl, the ratio is 1 mole of Zn to every 2 moles of HCl. So if there are 8.25 moles of Zn, it is possible to find the moles of HCl by doing the following relation:

1 mole Zn ----- 2 moles HCl

8.25 moles Zn ----- x moles HCl

$\frac{1}{8.25}=\frac{2}{x}\Rightarrow1x=2*8.25\Rightarrow16.5\text{ moles}$

16.5 moles of HCl are needed to react with 8.25 moles of zinc.