A sample of an iron sulfide contains #2.561*g# of metal, and #2.206*g# of sulfur. What is the empirical formula of iron sulfide?

1 Answer
anor277
Jun 10, 2016

#Fe_2S_3#

Explanation:

#"Moles of iron"# #=# #(2.561*g)/(55.85*g*mol^-1)# #=# #0.0459*mol#

#"Moles of sulfur"# #=# #(2.206*g)/(32.06*g*mol^-1)# #=# #0.0688*mol#

If we divide thru by the lower molar quantity, we get, #FeS_(1.5)#. However, by definition, the empirical formula is the simplest WHOLE number that defines constituent elements in a species, so we double the formula to get WHOLE numbers:

#Fe_2S_3#.

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