A compound's empirical formula is #C_2H_5#. If the formula mass is 116 amu, what is the molecular formula?

1 Answer
anor277
Mar 30, 2016

#C_8H_20#

Explanation:

The molecular formula is always a multiple of the empirical formula, the formula obtained by experiment.

What does this mean? Well, that #("Empirical formula")_n# #=# #"Molecular formula"#.

So we solve for #n#.

#nxx{2xx12.011+ 5xx1.00794}*g*mol^-1# #=# #116*g*mol^-1#

#n# #=# #116/29# #=# #4#

#"Molecular formula"# #=# #4xxC_2H_5# #=# #C_8H_20# as required.

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