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

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Answer 1 · 2016-03-30T07:23:21

$C_8H_20$

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.

A compound's empirical formula is C_2H_5C_2H_5. If the formula mass is 116 amu, what is the molecular formula?