Chemistry problem??? (Empirical Formulas)?
I need someone to guide me with this chemistry problem (empirical formula)?
a 2.60 g sample of iron chemically combines with chlorine gas to form 7.55 g of an iron chloride.
a) What is the empirical formula of the iron chloride?
b) What is the Percent of mass chlorine in the sample??
Please try to explain, Thank you..
Comments
Mass of chlorine (Cl) = mass of iron chloride - mass of iron = 7.55 - 2.60 = 4.95 g Cl.
Convert g of Fe and g of Cl to moles by dividing by the atomic weights for each on the periodic table.
2.60 g Fe x (1 mole Fe / 55.85 g Fe) = 0.0466 moles Fe
4.95 g Cl x (1 mole Cl / 35.45 g Cl) = 0.140 moles Cl
Divide by the smaller number (0.0466) and you get a Fe:Cl ratio of 1:3. So the empirical formula is
FeCl3.
%Cl = (g Cl / g sample) x 100 = (4.95 / 7.55) x 100 = 65.6% Cl