I will first off admit I'm and idiot and this is basic stuff...but I haven't touched chemistry in about...6 years. I remember how to make stock solutions, and manipulate dilutions...but mix in another chemical and...yeah...

I need to be able to manipulate my 2 stock solutions to make buffers. I made 2 stock solutions of 500mM from the following:


Sodium Phosphate, Monobasic, Monohydrate Crystal (FW137.99)
Sodium Phosphate, Dibasic, Anhydrous (FW 141.96)

What I'm having problems is remembering how to find the correct ratio of Monobasic and Dibasic in order to make correct molarities and pH's. What formula's should I use?

So say for instance I want a .5M solution of pH 8.0. Help me out you smarty pants chemistry majors PLLLLEEEEASSSEE!!

[Edited on November 17, 2009 at 10:33 AM. Reason : .]

11/17/2009 10:32:34 AM

http://www.thewolfweb.com/message_section.aspx?section=7

11/17/2009 11:00:34 AM

pH = pKa + log [(A-)/(HA)]

11/17/2009 11:25:26 AM

Henderson hasselbach...? I'm not really sure how to set that up. Ok...maybe a .5M is dumb, that's just pH manipulation.


Say .2M? How would I actualy set up that equation? Does anyone have a class powerpoint or something I could buy?

11/17/2009 11:31:08 AM

geez.

8.0 = 7.2 + log [dibasic/basic]

10^.8 = [dibasic/basic]

6.3 = [dibasic] / [basic]

6.3mol dibasic + 1mol basic into whatever concentration you want.

[Edited on November 17, 2009 at 11:38 AM. Reason : duh...]

11/17/2009 11:35:12 AM

I think i started off...I'm an idiot

Thank you, tho

11/17/2009 11:40:24 AM

So...

for a pH 8.0 the ratio is just generally 6.3/1.

Thank you.

So this would create a .5M concentration at pH 8.0, correct?

11/17/2009 11:42:09 AM