Question

Iron (III) oxide, also known as rust can be removed from iron by reacting it with hydrochloric acid to produce iron (III) chloride and water. Fe2O3 (s) + 6HCl (aq) ---> 2FeCl3 + 3H2O (l) What mass of hydrogen chloride is required to react with 100 g of rust? a. 371g HCl b. 137g HCl c. 130g HCl d. 147g HCl

Answer 1

b. 137 g.

Step-by-step explanation:

• The balanced equation for the mentioned reaction is:

Fe₂O₃(s) + 6HCl(aq) → 2FeCl₃(s) + 3H₂O(l),

It is clear that 1.0 mole of Fe₂O₃ react with 6.0 mol of HCl to produce 2.0 moles of FeCl₃ and 3.0 moles of H₂O.

• We need to calculate the no. of moles of rust (100.0 g):

n = mass/molar mass = (100.0 g)/(159.69 g/mol) = 0.6262 mol.

Using cross multiplication:

1.0 mol of Fe₂O₃ react completely with → 6.0 mol of HCl, from stichiometry.

0.6262 mol of Fe₂O₃ produced with → ??? mol of HCl.

∴ The no. of moles of HCl = (6.0 mol)(0.6262 mol)/(1.0 mol) = 3.757 mol.

∴ The mass of HCl needed = no. of moles x molar mass = (3.757 mol)(36.46 g/mol) = 137.0 g.

So, the right choice is: b. 137 g.