## Calculation of p-nitrophenol

Discussion of all aspects of biological molecules, biochemical processes and laboratory procedures in the field.

biology_06er
Coral
Posts: 260
Joined: Tue Mar 21, 2006 9:33 am

### Calculation of p-nitrophenol

Hi there

I'm unsure how to work out this question

in my test tube I have 1.9mL of glycine buffer and 0.1mL of p-nitrophenol and then I am suppose to calculate how much p-nitrophenol (in nmol) is present!!! can someone please help

Info.
0.05m glycine buffer, pH 9.5
0.25mM p-nitrophenol, in 0.05M glycine buffer, pH 9.5
0.2M NaOH

Thanks
biology_06r

canalon
Inland Taipan
Posts: 3909
Joined: Thu Feb 03, 2005 2:46 pm
Ci x Vi=Cf x Vf

What you know:
Ci: initial concentration (1M is 1mol/L)
Vi: initial volume
Vf: final volume

What you wantto know:
Cf: final concentration

Solve the equation for Cf (not too hard) and if you are careful with the units (mM vs M and mL and L) you have your answer with the volume and the concentration you have your number of moles (beware of the units, once again).
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

sdekivit
King Cobra
Posts: 586
Joined: Sat Jul 30, 2005 7:16 pm
Location: holland
Contact:

### Re: Calculation of p-nitrophenol

biology_06er wrote:Hi there

I'm unsure how to work out this question

in my test tube I have 1.9mL of glycine buffer and 0.1mL of p-nitrophenol and then I am suppose to calculate how much p-nitrophenol (in nmol) is present!!! can someone please help

Info.
0.05m glycine buffer, pH 9.5
0.25mM p-nitrophenol, in 0.05M glycine buffer, pH 9.5
0.2M NaOH

Thanks
biology_06r

you added 0,1 mL 0,25 mM p-nitrophenol in 0.05 M glycine buffer, pH = 9.5 to 1,9 mL glycine buffer ?

if so, then the dilution factor is 20 and thus [PNP] = 0.0125 mM

--> in a volume of 2 mL, amount of mmol PNP = 0.0125 x 10^-3 * 2 = 2.5 x 10^-5 mmol

--> thus amount nmol PNP = 2.5 x 10^-5 * 10^6 = 25 nmol.