Question

What mass of zinc chloride could be produced if 25cm3 of hydrochloric acid of concentration 2.4 mol/dm3 reacts with excess zinc?

Answer 1

Concentration of HCl = 2.4mol/dm3

Since 1dm3 = 1000cm3 = 1L

Moles of HCl in 25cm3;

2.4 mol are in 1000cm3

? mol will be in 25cm3

$=\dfrac{2.4 mol x 25cm^3}{1000cm^3} = 0.06mol$

Equation for the reaction

Zn_(s) + 2HCl_(aq) $\to$ ZnCl_2(aq) + 2H_2(g)

Mole ratio of HCl to ZnCl2 is; 2:1

Moles of ZnCl2 = $\dfrac{1}{2}x0.06 = 0.03mol$

Mass of ZnCl2 = moles x molar mass

= 0.03 mol x 136.286g/mol

= 4.089g