Question #6dead

1 Answer
Mar 1, 2015

You'd need 940 g of zinc metal to react completely with that particular HCl solution.

The starting point will be your balanced chemical equation

Zn(s)+2HCl(aq)ZnCl2(aq)+H2(g)

Now look at the 1:2 mole ratio that exists between zinc and hydrochloric acid; every mole of zinc needs 2 moles of hydrochloric acid for the reaction to take place.

This means that you can determine the number of moles of zinc that react by calculating the number of moles of hydrochloric acid that took part in the reaction.

You can do this by using the molarity of the HCl solution

C=nVnHCl=CV=3.5 M8.2 L=28.7 moles HCl

Using the mole ratio will get you

28.7 moles HCl1 mole zinc2 moles HCl=14.35 moles zinc

Calculate the mass of zinc by using its molar mass

14.35 moles65.4 g1 mole=938.5 g zinc

Rounded to two sig figs, the answer will be

mzinc=940 g