[brasarehot]

I'm stuck on four questions for my Biochemistry course. Helping me with one or all would be very helpful.
Here's my comments...
for Question 1) What is an undefined pH? I tried looking it up but got no where
for Question 2) How do you calculate pH for diprotic acid? Tried looking it up, but I got confused.
for Question 3) Clueless
for Question 4) How do you do titration for a base and acid with no conjugates like (PIPES/NaOH) instead of the usual (NaCH2COOH/CH3COOH)?
If you do answer please do full step by step math.
QUESTIONS...
1)What is the pH of 17M acetic acid? ANSWER: Undefined
2)Calculate pH of 0.05M oxalic acid? ANSWER: 1.5
3)The solubility of CO2 in water under standard conditions is 1.45g/L (partial CO2 pressure 1 atm). Assuming that air contains 0.039% of CO2, calculate the pH of water exposed to the air at standard conditions. ANSWER: 5.66
4)You titrate 1L of 1M PIPES by 10N NaOH. Calculate the pH of solution when 50ml of NaOH is added. ANSWER: 13.58

[Arkcon]

OK, lets start with #1.  You have a molarity, but the pH is undefined.  Why is that?  Hint:  look up the definition of pH.

[fledarmus]

For #4, what exactly do you mean by a "base and acid with no conjugates"? Are you saying that you do not know what the conjugate base of piperazine-N,N′-bis(2-ethanesulfonic acid) is?

And this might be an oversight, but it might also indicate why you are having a problem - "the usual (NaCH2COOH/CH3COOH)" should read "the usual (CH3COONa/CH3COOH)?" - the conjugate base of acetic acid is CH₃COO_-. You are not pulling a proton from the methyl group but from the carboxylic acid group. If you look up the structure of PIPES on wikipedia, you may understand why this is important.