Calculate the volume of hydrogen that is formed when 50 g of Zn containing 13%

Calculate the volume of hydrogen that is formed when 50 g of Zn containing 13% impurities are dissolved in hydrochloric acid.

Given:

m (Zn) = 50g

w% (impurities) = 13%

To find:

V (H2) -?

Decision:

Zn + 2HCl = ZnCl2 + H2, – we solve the problem, relying on the composed reaction equation:

1) Find the mass of pure zinc:

If the proportion of impurities is 13%, then the proportion of pure substance is 87%,

then m (Zn) = 50 g * 0.87 = 43.5 g

2) Find the amount of zinc:

n (Zn) = m: M = 43.5 g: 65 g / mol = 0.67 mol

3) We compose a logical expression:

If 1 mole of Zn gives 1 mole of H2,

then 0.67 mol Zn will give x mol H2,

then x = 0.67 mol.

4) Find the volume of hydrogen released during the reaction:

V (H2) = n * Vm = 0.67 mol * 22.4 L / mol = 15 L.

Answer: V (H2) = 15 liters.