Chemistry

posted by .

Given that 20 ml of a weak acid (HA) was titrated with NaOH and the titration curve of pH vs titrant volume in ml is given, find the initial concentration of the acid?

The problem gives the full titration curve starting at pH=2.2 at 0 ml added and with the equivalance pt at pH=7 at 18 ml added.

  • Chemistry -

    I'm at a distinct disadvantage since I can't see the titration curve but I think this is what you do.
    The equivalence point is 7 (which I really don't understand since weak acids and strong bases are supposed to be somewhere in the 8.3 range for the eq pt but this is probably just a made up problem). However, with the eq pt at 7.0 and 18 mL., take 1/2 of the 18 and look up on the curve for the pH at 9.0 mL. That will give you the pKa value. Convert that to Ka by pKa = -log Ka.
    Then convert pH 2.2 to (H^+) and plug that into the Ka equation of
    Ka = (H^+)(A^-)/[(HA)-(H^+)] and solve for HA.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Chemistry

    Part A: Unknown Acid use 1gram and mix with 120 mL of distilled water Determine the concentration of the acid by titrating with 0.0998 M of NaOH Concentration of NaOH= 0.0998M Volume of NaOH= 3.5 mL # moles of NaOH= Initial Concentration …
  2. Chemistry

    I there, this is my lab worksheet, I am having trouble filling it out. Please help me with it. Expt #1- Molecular Weight of Unknown Acid Unknown Acid: #3 Mass of Unknown solid acid transferred:1.0g Volume of volumetric flask: 100.00 …
  3. Chemistry

    A 30.00-mL sample of weak acid is titrated with 0.0167 M NaOH. At the endpoint , it is found the 40.35 mL of titrant was used. What was the concentration of the weak acid ?
  4. Chemistry, pH, Buffers

    Please help!! Given this data: mass of unknown acid 1.4671g Volume of NaOH used in titration 18.47mL Concentration of the NaOH used 0.2403M pH of the original acid solution 2.16 pH of the final acid solution 3.49 Show me how do I calculate …
  5. chemistry

    I am giving a titration curve of a weak base and strong acid. The pH on the y scale is from 0-14 and the volume of titrant in mL is from 0-34. It looks like the equivalene point is around 22?
  6. Chemistry

    1 g of acid was mixed with 120 ml of distilled water and the solution was filtered into a clean dry beaker. A 25 ml aliquot of this solution was titrated with 0.1120 M NaOH. The pH of the acid was recorded to be 4.42. Calculate the …
  7. Chemistry

    Find the concentration of the polyprotic weak acid given the following: - 1 equiv needs 6 ml NaOH, 2 equiv needs 18 ml NaOH, 3 equiv needs 28 ml NaOH - pKa1 = 2, pKa2 = 3.9, pKa3, 10 - Molarity of NaOH = 0.175 - Total volume of NaOH …
  8. Chemistry

    How do you find the initial concentration of the acid give the titration curve of a weak acid-strong base titration?
  9. chemistry 2

    Titration of 50.0 mL of acetic acid reaches equivalence after delivery of 22.5mL of standardized NaOH 0.21 M. What is the initial concentration of acetic acid and what is the pH of the solution?
  10. Chemistry

    The equivalence point of any acid titrated with a base occurs when the A. concentration of the acid and concentration of the titrant are equal. B. mass of the acid and the mass of the titrant are equal. C. pH of the mixture of the …

More Similar Questions