Question

What concentration (molarity) of Zn 2+ is present in solution when 5.00 g of zinc metal is used to displace hydrogen from 100 mL of 0.500 M HCl(aq)?

Answer 1

Zn + 2HCl        ZnCl₂ + H₂

Moles of Zn = Mass/Molar mass = 5 /65.38 = 0.0764 moles

Moles of HCl = Molarity x Volume in Liter = 0.5 x 0.1 = 0.05 moles

One mole of Zinc react with two moles of HCl to form one mole of Zn²⁺

0.0764 moles of Zn require, 2 x 0.0764 = 0.1528 moles. Therefore, HCl is the limiting reagent.

0.05 moles of HCl react to form 0.025 moles of Zn²⁺

Therefore, concentration of Zn²⁺ = Moles/Volume in Liter = 0.025/0.1 = 0.25 M

answered by: anonymous