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# Dilution help, hopefully simple problem.. watch

1. I'm using Oxalic Acid in an experiment, however I need to dilute it to be 0.1 mol per dm^-3.

I've been given the acid in a solid crystal dihydrate form.

I'm just wondering how I'd go about knowing how much to use to then be diluted by water.

Say I'm going to make up 1dm^3 of 0.1 mol dm^-3 Oxalic Acid solution..

The molar mass of Oxalic Acid is 90, and of the dihydrate i've been given - 126.

Is my working out below right for the amount of dihydrate I need to add to the water in order to make the solution?

Moles = Volume x Concentration
m = 1 x 0.1 = 0.1 moles.
Moles = Mass / Molar Mass
0.1 = x / 126

126 x 0.1 = mass of Oxalic Acid Dihydrate needed.
= 12.6g

Does that seem right to you?

2. looks good
3. Okay, cheers.. I just wanted to check as I wasn't sure if the 2H2O affected things other than the molar mass in the formula..
4. (Original post by mituozo)
Okay, cheers.. I just wanted to check as I wasn't sure if the 2H2O affected things other than the molar mass in the formula..
No when dissolved the acid will become 'separate' from the hydrating water molecules but you will still end up with 0.1 mole of the required acid

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