Question

When zinc powder (ZnO + Zn) is dissolved in dilute H₂SO₄, then 150 mL H₂ gas is released at NTP. Calculate the percentage of Zn in zinc powder? (Atomic mass of Zn = 65 g mol^-1).

Answer 1

Both Zn and ZnO react with dil. H₂SO₄ but only Zn releases H₂ gas.

∵ Amount of Zn, required to release 22400 mL H₂ gas = 65 g

∴ for 150 ml H₂ \( = \frac{65\times 150}{22400} = 0.435\ g\)

% of Zn in zinc powder = 

= 87%