A chromium chloride salt contains #32.8%# metal content by mass. What is its empirical formula?

1 Answer
Mar 30, 2017

Answer:

We assume a #100*g# mass of compound, and get an empirical formula of #CrCl_3#.

Explanation:

In all problems of this sort, it is convenient to assume a #100*g# mass of compound, and then work out the individual molar quantities of each element:

#"Moles of chromium"=(32.8*g)/(52.0*g*mol^-1)=0.631*mol#

#"Moles of chlorine"=(67.2*g)/(35.45*g*mol^-1)=1.90*mol#

We divide thru by the SMALLEST molar quantity, that of the metal, to get an empirical formula of #CrCl_3#.