Question

Zinc reacts with hydrochloric acid to form zinc chloride and hydrogen. What mass of zinc chloride could be produced if 25cm² of hydrochloric acid of concentration 2.4 mol dm‐³ reacts with excess zinc

Answer 1

The reaction could be expressed as:

$Zn+2HCl\rightarrow ZnCl_{2}+H_{2}$

The amount of HCl in moles is:

$\nu(HCl)=V(HCl)\cdot C(HCl)=0.025 dm^{3}\cdot2.4mol/dm^{3}=0.06 mol;$

The amount of ZnCl₂ in moles is:

$\nu(ZnCl_{2})=\frac{1}{2}\cdot\nu(HCl)=0.03mol;$

The molar mass of ZnCl₂ is:

$M(ZnCl_{2})=136g/mol;$

Thus, the mass of ZnCl₂ produced is:

$m(ZnCl_{2})=\nu(ZnCl_{2})\cdot M(ZnCl_{2})=4.08g.$