# Question #4bd23

##### 2 Answers

The empirical formula is

Write down the ratio of the elements by mass.

%C = 100 - 7.74 = 92.26.

Ratio C : H by mass:

C : H = 92.26 : 7.74

To get the ratio by moles we divide by the

Ratio C : H by moles:

=

Dividing through by 7.69 we get:

1 : 1.006 which we can round down to:

1 : 1

So the empirical formula is

To find the molecular formula we find how many

So the molecular formula is

The empirical formula is

Since we know that a hydrocarbon only contains carbon and hydrogen, we can use the percent of hydrogen given to determine how much carbon the compound contains

The next step in determining the empirical formula is to divide each element's percentage by its atomic mass

You then divide each of these two numbers by the smallest one to get the ratios of the two elements in the molecule:

This is your empirical formula:

This is done by using benzene' molar mass to determine the value of

Therefore, your molecular formula is