Question

a compound has a molar mass of 39 g/mol and an empirical formula of CH. What is the molecular formula?

Answer 1

Answer:

$C_3H_3\text{ }$

Explanation:

Here, we want to get the molecular mass of the compound given its empirical formula

The difference between the two is simply the subscript attached to the atoms which is the number of these atoms

Let us call the number n

We should recall that the atomic mass unit of carbon is 12 amu , while the atomic mass unit of hydrogen is 1 amu

In its final outlook, the molecular formula would be:

$(CH)_n$

We can use the individual amu to get the value of n

$\begin{gathered} n(12\text{ + 1) = 39} \\ 13n\text{ = 39} \\ n\text{ = }\frac{39}{13} \\ \\ n\text{ =3} \end{gathered}$

Thus means the molecular formula of the compound is:

$C_3H_3\text{ }$