Question

4. Determine the molecular formulas for compounds having the following empirical formula and molar mass:

CH4O; experimental molar mass 128 g/mol

Answer 1

please

Answer 2

The 'experimental molar mass' is the molar mass you will need to be aiming for to get the molecular formula.

So you need to get to a compound that will have a molar mass of 128 g/mol

Firstly, find the molar mass of the compound you have already in empirical formula.
C + 4H + O
12 + 4 + 16 = 32 g/mol

So your empirical formula compound has 32 g/mol, but you need to find the compound that has 128 g/mol.

So now, you will need to do: the molar mass you need / molar mass of empirical formula
128/32 = 4

So 32 goes into 128 FOUR times. This means you will need to times your empirical formula (CH4O) by 4, to get the compound with a molar mass of 128 g/mol.

\[C \times 4 = C _{4}\]
\[H _{4} \times 4 = H_{16}\]
\[O \times 4 = O _{4}\]

Now, put it all together in the same order:
\[C _{4}H _{16}O _{4}\]

That will be your molecular formula with a molar mass of 128 g/mol

I hope this helps! :)