Question

Hydrochloric acid can dissolve solid iron according to the following reaction.
Fe(s)+2HCl(aq)→FeCl2(aq)+H2(g)

(Part A) What minimum mass of HCl in grams would you need to dissolve a 2.7 g iron bar on a padlock?

(Part B) How much H2 would be produced by the complete reaction of the iron bar?

Answer 1

molar mass of Fe = 55.8 g/mol
number ofmole of Fe = (given mass)/(molar mass)
= 2.7/55.8
= 0.048 mole

reaction taking place is
Fe(s)+2HCl(aq)→FeCl2(aq)+H2(g)
A)
according to reaction
1 mole of Fe required 2 mole of HCl
0.048 mole of Fe required (2*0.048) mole of HCl
number of mole of HCl required = 0.096 mole

molar mass of HCl = 36.5 g/mol
mass of HCl = (number of mole of HCl)*(molar mass of HCl)
= 0.096*36.5
= 3.5 g

Answer : 3.5 g
b)
according to reaction
1 mole of Fe give 1 mole of H2
0.048 mole of Fe give 0.048 mole of H2
number of mole of H2 produced = 0.048 mole

molar mass of H2 = 2 g/mol
mass of H2 produced = (number of mole of H2)*(molar mass of H2)
= 0.048*2
= 0.096 g

Answer : 0.096 g