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Did I mess up my Physics experiment?

So I have these physics experiments to do, and one of them needed me to make up a certain molarity of a substance. The experiments we are set are pretty random and I'm not really enjoying the labs so far. Basically I had to create certain molarity solutions and this module doesn't (or shouldn't) require any forknowledge of chemistry.

I have lots of other experiments to do, and this is just one part of one experiment so I'm not trying to cheat my way through or anything but in the experiment I had to end up putting in any random amount that felt right. I'd just like to know what the correct amounts should have been, and how far I've potentially messed up this experiment.

I have(had) a bottle of pure ethanol and propan-1-ol which have densities of 789 and 804 kg/m respectively and molecular weights of 46 and 60 respectively. I needed to make up 0.8M solutions of each using distilled water. Using a marked-liquid-sucker I could take x ml of each liquid. What ml should I have taken to put in, say, 100 ml of water?

Thanks to anyone who can help!!
Reply 1
Avatar for vVPiKaVv
vVPiKaVv
1
0.8M = 0.8 mol/litre
By ratio, you'll need 0.08 mol in 100 ml of water.
Mole = mass/Mr, so for example ethanol,
Mass of ethanol needed = 46 x 0.08 = 3.68g
Work out the volume required, but take note of the units!
3.68g = 0.0038 kg
Work out the volume in m³ required and you'll get 4.82 x 10^-6 m³..convert it to cm³ (since cm³ = ml) and you'll need 4.82 ml of ethanol.

Try working it out for propan-1-ol =)

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