Chapter 4, Problem

Zinc and magnesium metal each react with hydrochloricacid according to the following equations:

$\begin{array}{l}\text{Zn(}s\text{)+2HCl(}aq\text{)}\to {\text{ZnCl}}_{\text{2}}\text{(}aq{\text{)+H}}_{\text{2}}\text{(}g\text{)}\\ \text{Mg(}s\text{)+2HCl(}aq\text{)}\to {\text{MgCl}}_{\text{2}}\text{(}aq{\text{)+H}}_{\text{2}}\text{(}g\text{)}\end{array}$

A 10.00-g mixture of zinc and magnesium is reactedwith the stoichiometric amount of hydrochloric acid.The reaction mixture is then reacted with 156 mL of3.00 M silver nitrate to produce the maximum possibleamount of silver chloride.
a. Determine the percent magnesium by mass in theoriginal mixture.
b. If 78.0 mL of HCl was added, what was the concentrationof the HCl?