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# How the hell do I work this out? watch

1. Calculate the amount ot Triethanol (Molecular weight = 149.19) required to make 500mls of a 200mM solution.

I don't even know where to start!
2. (Original post by ChemEng90)
Calculate the amount ot Triethanol (Molecular weight = 149.19) required to make 500mls of a 200mM solution.

I don't even know where to start!
mol of solid = mass in g / molar mass in g per mol

mol of solutions = concentration in mol per dm cube x volume in dm cube

Find mol of the solution you want to make, then equate with mol of solid, find the mass of solid required in g. Though I imagine, triethanol is probably liquid?
3. ...Rep to anyone who can works this out. I'm baffled!!!
4. Work out how many moles you need

500 mL/0.5 dm3 and 200 x 10-3 mol dm-3

concentration = moles/volume
5. (Original post by EierVonSatan)
Work out how many moles you need

500 mL/0.5 dm3 and 200 mol dm-3

concentration = moles/volume
Rewrite the second line please, it's not clear mate. It's partly coming back to me now lol.
6. hmm, elementary chemist
7. This isn't for me, it's for a friend lol. I don't do Chemistry, nor have time for it lol.
8. I've been trying to edit that post for 15 minutes

fixed
9. ....scratch that LIE. Retardation and tiredness set in.
10. Thanks EierVonSatan and shengoc. I'll rep you both.
11. The term 'Molecular weight' threw me off completely, cos I'm used to seeing molecular mass.

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