# Calculation - (Oct/16/2007 )

Hi there,

Got a test coming up (tomorrow) and am going through some calculations and am unsure of this on...

If the molecular weight of drug X is 255 Da, how much would you need to make 50mL of a 10mM solution?

So from the example we get I gather I have to go something like:
255Da=255g/L=255mg/mL=1mM (this is probably wrong though?)

And then I am lost so any help is much appreciated!

Cheers,

-biology_06er-

QUOTE (biology_06er @ Oct 16 2007, 01:18 PM)
Hi there,

Got a test coming up (tomorrow) and am going through some calculations and am unsure of this on...

If the molecular weight of drug X is 255 Da, how much would you need to make 50mL of a 10mM solution?

So from the example we get I gather I have to go something like:
255Da=255g/L=255mg/mL=1mM (this is probably wrong though?)

And then I am lost so any help is much appreciated!

Cheers,

1 Da is 1gr/mol
Molarity=number of moles/volume in litres, so 1M=1mol/1 liter 1mM=1mmol / 1 liter
so for 10mM you need 10 mmoles in 1 liter. from this you can calculate how many moles (or mmoles) you actually need for 50ml. always remember that C1V1=C2V2 where C: concentration and V: volume.

As I understand I'm not supposed to give you the results, but help to get there, so now I let you calculate how many moles you need to have 10mM in 50ml and how many grs of your drug that'll be considering it is 255gr/ml (Da).

Good luck!

-almost a doctor-

QUOTE (almost a doctor @ Oct 16 2007, 08:28 AM)
QUOTE (biology_06er @ Oct 16 2007, 01:18 PM)
Hi there,

Got a test coming up (tomorrow) and am going through some calculations and am unsure of this on...

If the molecular weight of drug X is 255 Da, how much would you need to make 50mL of a 10mM solution?

So from the example we get I gather I have to go something like:
255Da=255g/L=255mg/mL=1mM (this is probably wrong though?)

And then I am lost so any help is much appreciated!

Cheers,

1 Da is 1gr/mol
Molarity=number of moles/volume in litres, so 1M=1mol/1 liter 1mM=1mmol / 1 liter
so for 10mM you need 10 mmoles in 1 liter. from this you can calculate how many moles (or mmoles) you actually need for 50ml. always remember that C1V1=C2V2 where C: concentration and V: volume.

As I understand I'm not supposed to give you the results, but help to get there, so now I let you calculate how many moles you need to have 10mM in 50ml and how many grs of your drug that'll be considering it is 255gr/ml (Da).

Good luck!

watch your units. 255g/l=255mg/ml=1M (not mM).
also aad is mostly correct, except for the last: it is 255g/l (not ml).

-mdfenko-

QUOTE (mdfenko @ Oct 16 2007, 03:04 PM)
QUOTE (almost a doctor @ Oct 16 2007, 08:28 AM)
QUOTE (biology_06er @ Oct 16 2007, 01:18 PM)
Hi there,

Got a test coming up (tomorrow) and am going through some calculations and am unsure of this on...

If the molecular weight of drug X is 255 Da, how much would you need to make 50mL of a 10mM solution?

So from the example we get I gather I have to go something like:
255Da=255g/L=255mg/mL=1mM (this is probably wrong though?)

And then I am lost so any help is much appreciated!

Cheers,

1 Da is 1gr/mol
Molarity=number of moles/volume in litres, so 1M=1mol/1 liter 1mM=1mmol / 1 liter
so for 10mM you need 10 mmoles in 1 liter. from this you can calculate how many moles (or mmoles) you actually need for 50ml. always remember that C1V1=C2V2 where C: concentration and V: volume.

As I understand I'm not supposed to give you the results, but help to get there, so now I let you calculate how many moles you need to have 10mM in 50ml and how many grs of your drug that'll be considering it is 255gr/ml (Da).

Good luck!

watch your units. 255g/l=255mg/ml=1M (not mM).
also aad is mostly correct, except for the last: it is 255g/l (not ml).

1Da is 1gram in 1 mol, so 255Da is 255gr/mol (sorry no ml).

-almost a doctor-

Thanks for the help,

so can I do this...seeing as I have the conc. and volume and want the number of mols...is this right?

CXV=10mmol/Lx0.05L=0.5molsx255Da(=255g/L=255mg/ml)=127.5mg???

-biology_06er-