how many grams of iron are needed to produce

Question

How many grams of iron are needed to produce 36.4 L of hydrogen gas according to the following reaction at 25 °C and 1 atm?

iron (s) + hydrochloric acid(aq)iron(II) chloride (aq) + hydrogen(g)

______ grams iron

Answer 1

Fe(s) + 2HCl(aq) ==> FeCl₂(aq) + H₂(g) ... balanced equation

Using the ideal gas law, we can find the moles of H₂ gas produced. Then using the stoichiometry of the balanced equation, we can find moles Fe needed to produce that many moles H₂ gas and finally, we can convert moles of Fe to grams of Fe using the atomic weight of Fe.

PV = nRT

P = 1 atm

V = 36.4 L

n = ?

R = 0.0821 Latm/Kmol

T = 25 + 273 = 298K

n = PV/RT = (1)(36.4)/(0.0821)(298)

n = 1.49 moles of H₂

1.49 moles H₂ x 1 mol Fe / 1 mol H2 = 1.49 moles Fe

1.49 moles Fe x 55.85 g/mol Fe = 83.2 g Fe needed