Chemistry Forum

Please help me with this question:
Given the empirical formula CH₂O, what is the molecular formula of the compound?
Thanks in advance.

Could be everything. Not much Information.
X = 1 its formaldehyde
X = 6 its C₆H₁₂O₆ one sogar like glucose, fructose, and others

For example, if the molar mass of the compound is found to be 30 g/mol, then the molecular formula would be the same as the empirical formula because the molar mass of the compound equals the molar mass of the empirical formula unit:

Molecular formula = Empirical formula = CH₂O

If the molar mass is different, we would need to determine how many empirical formula units are present in the molecular formula by dividing the molar mass of the compound by the molar mass of the empirical formula.

Number of empirical units = Molar mass of compound/Molar mass of empirical formula
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If the molar mass is 30 g/mol it is formaldehyde.
C (12)H(1)O(16) 12+2+16=30.

But it wasn't
It was 60 g/mol

Why? If it is formaldehyde it will be 30g/mol.

Because the teachers has given it.

I not understand. Molar mass of formaldehyde is 12+1+1+16 = 30 g/mol? Where is the magic?

The empieric formula is 30 g/mol, but the measured molar mass was 60 g/l.

It could be also 180 g/mol if it is a sugar C₆H₁₂O₆ means 6 x CH₂O.
Empieric formula says nothing about the real molecule. Only with 30 g/mol it could be formaldehyde.

If molar mass is 60 g/mol it may be something like this: OH-CH=CH-OH. But i not found this substance in the internet. I search for acetyleneglicol i found that acetyleneglicol is exist but i didn't found it's formula.

Also it may by aldehyde: OH-CH₂-CO-H but i really not found what substance is.

Possibilities CH₃COOH, acetic acid, HCOOCH₃ Methylformiate, HOCH₂CHO Glycolaldehyde,

Oh! I forget acetic acid! This substance is (CH₂O)*2.

If it was scool task then acetic acid as more simple substance.

To find the molecular formula from the empirical formula, you need to know the molar mass of the compound. The empirical formula CH₂O has the following molar masses:

Carbon (C): 12.01 g/mol
Hydrogen (H): 1.01 g/mol
Oxygen (O): 16.00 g/mol

So, the total molar mass of CH₂O is:
(12.01 g/mol) + 2*(1.01 g/mol) + 16.00 g/mol = 30.03 g/mol

Now, you need to compare the molar mass of the empirical formula to the molar mass of the compound to determine the ratio between them.

Let's assume the molar mass of the compound is 60.06 g/mol (just for example).

The ratio between the molar mass of the compound and the empirical formula is:
(60.06 g/mol) / (30.03 g/mol) = 2

So, the molecular formula will have twice the number of atoms as the empirical formula. Therefore, the molecular formula of the compound is:

C₂H₄O₂