#### help please...chemistry! fed up now.

P

can anyone help me i need to convert ng/ul to moles.. my supervisor called me stupid and walked off when i asked him.

C

Do you have the molecular weight of the substance?

P

yes i do?

A

hi phd girlie, never fear ur not stupid! Im just useless when it come to moles as well. as far as i know, u need to calculate the molar mass on one mole, so thats just the molecular weight of whatever substance u have, then u use this to find out what the relative mass of the amount of the substance is and thats ur molar mass.

eg, 5.380g of C6H12O6. molar mass of C6H12O6 is 180.0g/mol. ing 1 mol C6H12O6 = 180.0 g of C6H12O6, moles C6H12O6 = (5.380)*(1molC6H12O6/180.0g C6H12O6) = 0.02989mol C6H12O6.

hope that helps!

T

http://www.genscript.com/conversion.html

This might be of some help

J

P

thank you

P

yeah he is a muppet, a unhelpful one at that.. and then he wonders why i am scared to ask questions! feel to stupid crying over calculations!

J

It can take years to get used to certain calculations (some people can do them without thinking; most of us can't). I know elderly profs who confess to struggling and having to spend whole afternoons going over them. Better you ask for help than try to blag your way through - any supervisor who doesn't realise that is failing as a supervisor (and is a jerk).

J

There is a book (with a tile something likw Calculations for A-Level Chemistry) that I found really helpful. Unhelpfully I forget the exact name of it and I'm not in the lab this week, but next week I'll post the details, unless someone else can remember it.

P

thanks that would be great. ive tried to ask him in the past and he looks at me like im derranged. he knows i dont have a strong chemistry background, but the rolling of the eyes when i ask doesnt encourage me to ask!

C

Have you tried finding a friendly postdoc or another lab member to ask questions?

P

unfortunatly there are none! the postdoc in our group is based in another lab but is on holiday for a month!