Question

A chemist reacts 8.85 g of iron with an excess of hydrochloric acid to form hydrogen gas and iron(II) chloride. Calculate the theoretical yield and the percent yield of hydrogen if 0.27 g of H2 are collected.

TY = g H2 PY = %

Answer 1

The theoretical yield and percent yield of hydrogen if 0.27 g of H2 collected is calculated as follows

write the reaction equation

that is Fe + Hcl = H2 + FeCl2

calculate moles of Fe = mass/molar mass = 8.85 g/56 g/mol =0.158 moles

by use mole ratio between Fe : H2 which is 1:1 the theoretical moles of hydrogen = 0.158moles
the theoretical mass is therefore = moles x molar mass
= 0.158 mol x2g/mol =0.316 grams

% mass = actual mass/ theoretical mass x 100

= 0.27/0.316 x100 = 85.4 %