Question

A common laboratory preparation of hydrogen on a small scale uses the reaction of zinc with hydrochloric acid. Zinc chloride is the other product.

(a) If 13.0 L of H2 at 765 torr and 20.0 °C is wanted, how many grams of zinc are needed, in theory?


(b) If the acid is available as 8.59 M HCl, what is the minimum volume of this solution (in milliliters) required to produce the amount of H2 described in part (a)?

Answer 1

Zn + 2HCl ==> H2 + ZnCl2
Use PV = nRT and solve for n = number of mols H2 at the conditions listed. Convert mols H2 to mols Zn, then
g Zn = mols Zn x atomic mass Zn.

b)
Convert mols H2 to mols HCl, then M HCl = mols HCl/L HCl. Solve for L and convert to mL.