A compound having an empirical formula of #C_3H_4O_3# has a mass of 180 g/mol. What is the molecular formula?

1 Answer
anor277
Jun 4, 2016

#"Molecular formula"# #=# #C_6H_8O_6#

Explanation:

The molecular formula is always a whole number multiple of the empirical formula:

i.e. #"Molecular formula"# #=# #"(Empirical formula)"xxn#

So we need to solve for #n#.

Thus #180*g*mol^-1# #=# #nxx(3xx12.011+4xx1.0079+3xx15.999)*g*mol^-1#
#=# #nxx(88.0)*g*mol^-1#

#n~=2#. Thus #"Molecular formula"# #=# #C_6H_8O_6#.

Of course, the ratio is out a little bit. Such errors are common in the determination of such formulae.

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