# Help needed!!!!

University course discussion for Pharmacy.

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1. Help needed!!!!
If you were asked to prepare 500 mL of a 100 M stock solution of drug Y (molecular
weight 180), calculate how many milligrams of drug Y you
would need to weigh out in order to make this solution. SHOW YOUR
CALCULATIONS.

Can anyone help on the above question??
I'm really stuck and need help as I have a resit coming up
thanksxxx
2. Re: Help needed!!!!
100 M stock solution
100M? or should it be milimoles? Because a 100M solution is quite uncommon
3. Re: Help needed!!!!
ooops, it shud be 100micromolar
can u help? its driving me mad!
4. Re: Help needed!!!!
anyone?
5. Re: Help needed!!!!
9 mg
6. Re: Help needed!!!!
(Original post by Cetomacrogol)
9 mg

calculations:

M= 180 g/mol
V=500ml= 0,5 dm~3
c= 0,0001 M/ dm~3

quantity (in moles) of drug Y in 0,5 dm3 of the solution:

x= 0,0001 mol * 0,5 dm~3
------------------------
1dm~3

x= 0,00005 mol

mass of drug Y in o,5 dm~3 of the solution:

m= 0,00005 mol * 180g/mol = 0,009g= 9mg

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Last updated: September 6, 2007
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