Question

A sample of iron metal is placed in a graduated cylinder. It is noted that 10.4 mL of water is displaced by the iron. The iron is then reacted with excess hydrochloric acid to produce iron (II) chloride and hydrogen gas. Given the density for iron is 7.86 g/mL, how many grams of iron (II) chloride are produced in the reaction? Fe(s) + 2HCl(aq) - FeCl2(aq) + H2(g)

Answer 1

volume of Fe = volume of water displaced

= 10.4 mL

Mass of Fe reacted = density * volume

= 7.86 g/mL * 10.4 mL

= 81.744 g

Molar mass of Fe = 55.85 g/mol

mass of Fe = 81.74 g

mol of Fe = (mass)/(molar mass)

= 81.74/55.85

= 1.464 mol

According to balanced equation

mol of FeCl2 formed = moles of Fe

= 1.464 mol

Molar mass of FeCl2,

MM = 1*MM(Fe) + 2*MM(Cl)

= 1*55.85 + 2*35.45

= 126.75 g/mol

mass of FeCl2 = number of mol * molar mass

= 1.464*1.268*10^2

= 1.855*10^2 g

Answer: 186 g