Anyone good at Chemistry Calculations

[minendo]

Can anyone point me in the right direction to solve the following problem.


[*]If it took 47mL of ca 0.1N NaOH solution to titrate 0.80g of patassium acid phthalate, what is the concentration of the undissociated acid form of KAP in the final titrated solution at the endpoint pH=8.1? The pKa of KAP = 5.4 and I have calculated the exact N of NaOH to be 0.0939.

Anyone know where to go from here? I know I need the equation pH = pKa + log (A-)/(HA), but I don't know how to get [A-].

 

[Moonbeam]

You get A- by not getting a perfect score but still doing pretty well.

 

[Moonbeam]

^

 

[Zebo]

What is this quantitative analysis?

 

[everman]

Thursday.

 

[DoNotDisturb]

i actually did bad on the concentration chapters dealing with logs (i didn't have that experience with logarithms yet) sorry..... however, if you have any problems with molarity, molality, etc... you can ask.

 

[minendo]

Originally posted by: Carbonyl
What is this quantitative analysis?

It's actually a problem of Titrable Acidity from my FS 467 - Food Analysis course.

 

[Dudd]

Sorry man, AP Chem was last year. I've spent all of this year trying to forget everything I learned last year.

 

[minendo]

Originally posted by: Dudd
Sorry man, AP Chem was last year. I've spent all of this year trying to forget everything I learned last year.

Sad thing being that I've had four years of Chem plus biochem and quantitative analysis and I can't remember exactly how to do it.

 

[Zebo]

Originally posted by: minendo

Originally posted by: Carbonyl
What is this quantitative analysis?

It's actually a problem of Titrable Acidity from my FS 467 - Food Analysis course.

Are you using the eqaution for weak acids?
[H+][A-]
_______ = K
[HA]

K= 10^-pKa

or 3.10X10^-6

 

[vtqanh]

and [H+] = [A-], you should have Ka = [H+]^2/[HA]. It's been too long (5 years) since i did any chemistry calculation...