Okay, 88 g/mol tells you that the total molecular weight of the atoms in the molecule will add up to 88.

Now, the molecular weight of carbon is just over 12, and the molecular weight of oxygen is just under 16. The number of atoms of each in a molecule must be a positive integer.

12c + 16o = 88 where c, o are in [1,2,3,4,5...]

3c + 4o = 22 so c must be even (or the left side of the equation is odd)

and c must be less than 7 [2,4,6]

o = (22 - 3c) / 4

If C is 2, then O is (22-6)/4 = (16/4) is 4

If C is 4, then O is (22-12)/4 = (10/4) is not an integer

If C is 6, then O is (22-18)/4 = (4/4) is 1

There are two possible formulae

C2O4

C6O

Of course, I get down here and ask myself where are the hydrogen? The Hydro in hydrocarbon is for hydrogen, and there MIGHT be oxygen in a hydrocarbon molecule - but there aren't always. No, in fact a ketone wouldn't be a pure hydrocarbon, it's a different kind of organic molecule.

Are you sure you read the problem right? Are there any other words involved?

Okay, from scratch.

The molecular weight of carbon is 12, so there are, at most, 7 carbons in the chain, weighing 7*12 = 84. That leaves a molecular weight of 4 for the hydrogen, giving us H4C7 as one possible formula. That's possible, but it's a weird formula - too few hydrogen for my taste.

If there are 6 carbons in the chain, we have 88 - 6*12 = 16 hydrogen, giving H16C6.

Now, normally in a simple hydrocarbon, there are 3 hydrogen on each end carbon and 2 in each center carbon, for a maximum number of 14 hydrogen for 6 carbon. I really dislike more hydrogen than that, because I don't remember that being possible for normal carbon valences.

I'm stumped how either of these answers makes sense.

Okay, C7H4 is legal. See comments.

Dal J.

11/12/14