How do you find the empirical formula without the molar mass?

=1.854g/.01236 moles = 150 g/mole

CH2O weighs 12+2 +16 = 30 g

150/30 =5

C5H10O5 yep ribose is a pentose

=1.854g/.01236 moles = 150 g/mole

CH2O = 12+2 +16 = 30 g

150/30 =5

Erm I'm not sure if that means, the 1.854g sample of D-ribose contains 0.01236 mol of D-ribose or if it means the 1.854g sample of D-ribose contains 0.01236 mol of some other sugar with empirical formula CH2O.

I can do the first one so I'll do that:

If you have 0.01236 mol of D-ribose, and its mass is 1.854g then the molecular mass must be:

1.854 / 0.01236 = 150. Hehe when you get a nice round number like that it does feel like you are on the right track.

So CH2O has Mr of : 30.

150 / 30 = 5. The molecular formula of D-ribose is: C5H10O5. Which is correct according to wikipedia.

As for the second suggestion. You know what I would stick to that answer, the other suggestion might be possible but it would take a lot of messing around with numbers and ratios and things which doesn't seem like a very good question if it just wants to know the molecular formula and the other one worked out so well I would put money on it being the thing it wanted. The wording was aweful but if you lay it out and have a look it does sometimes work out.