Chemistry help!!

posted by .

Consider the titration of the weak acid HA with NaOH. At what fraction of Ve does pH = pKa - 1? At what fraction of Ve does pH = pKa + 1? Calculate the pH at these two points plus Vb = 0, 1/2Ve, Ve and 1.2Ve, if 100 mL of 0.100 M anilinium bromide (pKa = 4.601) is titrated with 0.100 M NaOH. {Ve is Volume at equilibrium,Vb is volume of base}

  • Chemistry help!! -

    Surely you mean Ve = volume at the equivalence point.
    The Henderson-Hasselbalch equation is
    pH = pKa + log(base)/(acid)
    If pH = pKa, then log B/A = 0 and B/A = 1
    If pH = pKa + 1, then log B/A = 1 and B/A = 10
    If pH = pKa -1, then log B/A = -1 and B/A = 0.1

    ..........HA + OH^- ==> A^- + H2O
    initial....1.....0.......0......0
    add.............x..............
    change.....-x....-x......x.....x
    equil.....1-x.....0......x.....x

    The three cases above are done this way.
    When B/A = 1, then [(x)/(1-x)] = 1
    Solve for x and obtain x = 1-x so you are half way to the equivalence point.

    When B/A = 10, then [(x)/(1-x)]=10
    Solve for x = 0.90909 and that is the fraction to Ve.

    When B/A = 0.1, then......

    Set up an ICE chart and substitute moles into it for base and acid and use the HH equation to solve for pH for the specific points.
    Post your work if you get stuck.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. CHEMISTRY FOR DR. BOB or anyone else

    A hypothetical weak acid HA, was combined with NaOH in the following proportions: 0.20 mol HA, 0.08 mol NaOH. The mixture was then diluted to a total volume of 1L, and the pH measured. (a) If pH=4.80, what is the pKa of the acid (b) …
  2. chemistry - titration

    Show that for the titration of a weak acid, HA, with NaOH solution, at half-titer, pH = pKa. Please explain your answer. Thank you. HA + NaOH ==> NaA + HOH Ka for HA = (H^+)(A^-)/(HA) and solve for H^+. (H^+) = Ka*[(HA)/(A^-) When …
  3. 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 …
  4. college chemistry

    In the analysis of food, the nitrogen from the protein is sometimes converted into ammonia which is titrated against a strong acid. Given that the final NH3 concentration (approximate) is 0.2M and that pKa for NH4+ is 9.2, choose the …
  5. CHEMISTRY

    In the analysis of food, the nitrogen from the protein is sometimes converted into ammonia which is titrated against a strong acid. Given that the final NH3 concentration (approximate) is 0.2M and that pKa for NH4+ is 9.2, choose the …
  6. Chemistry

    Consider a weak acid-strong base titration in which 25.0 mL of 0.100 M acetic acid is titrated with 0.100 M NaOH. a) Calculate the pH after the addition of 3.00mL of NaOH. b) What is the pH of the solution before the addition of NaOH …
  7. Analytical Chemistry 2

    Consider the titration of the weak acid HA with NaOH. At what fraction of Ve does pH = pKa - 1?
  8. Chemistry

    100 mL of 1.0 M formic acid (HCOOH) is titrated with 1.0 M sodium hydroxide (NaOh). The Approximate pKa is 4 At the pKa, what fraction of the carboxyl group will have been converted to COO-?
  9. chemistry- titration

    Once you have calculated your Ka value, use the data to find the concentration of the unknown acids. Vol. of acid solution=25mL concentration of NaOH used = 1M Buffer (pH) = 8.35 at 11.5mL 1/2 11.5=5.75mL which is a pH of 3.58 I did …
  10. chemistry

    You discovered a new diprotic acid, which you have named edmontonic acid. You want to characterize the pKa’s of edmontonic acid, so you perform a titration experiment. Your data are summarized in the table below. Your titration sample …

More Similar Questions