if 4 volumes of 0.1M monobasic potassium phosphate, KH2PO4, are mixed with 2 volume of 0.1 M dibasic sodium phosphate, Na2HPO4, what will be the pH of the mixture?

What if 4 volumes of 0.1 M KH2PO4 are mixed with 8 volumes of 0.1 M ethanolamine base(pka=9.44) what will be pH of mixture?

  1. 0
  2. 3
asked by dIrk
  1. Use pH = pKa + log[(base)/(acid)]
    KH2PO4 is the acid. Na2HPO4 is the base.

    For b part:
    Write the reaction between KH2PO4 (the acid) and ethanolamine(the base) and see how much of each is left over and the amount of salt produced. Then plug into the HH equation.
    Post your work if you get stuck.

    posted by DrBob222
  2. what's the pKa?

    posted by dIrk
  3. pH= pKa + log 0.1M/0.1M
    what's the pKa value?

    posted by dIrk
  4. Won't that be pKa for k2 of H3PO4?
    The 9.44 is pKa for ethanolamine.

    posted by DrBob222
  5. pH=7.20+log0.1M/0.1M

    posted by dIrk
  6. base is not 0.1 and acid is not 0.1. Isn't the base 4 volumes x 0.1 = 0.4 moles; therefore, the concn is 0.4 moles/volume (whatever that is but it doesn't matter because the acid will be divided by the same V and V will cancel).

    posted by DrBob222
  7. pH=7.20+log 0.2M/ 0.4M

    I'm heading in the right direction?

    posted by dIrk
  8. Sorry the final pH of the mixture is 7.50, is that correct DrBob222?

    posted by dIrk
  9. the equation will look like this:

    pH=7.20+log 0.4/0.2
    = 7.50


    posted by dIrk
  10. I believe you, correct if I'm not mistaken on part A. The answer is 7.50.

    for part B: the Base is the amount of initial base minus the amount of base protonated.

    Maybe Dr.Bob should show us Visually . DR.BOB!!!

    posted by Jimmy

Respond to this Question

First Name

Your Response

Similar Questions

  1. chemistry

    Calculate the mass of salts needed for constructing a buffer using potassium monobasic phosphate and potassium dibasic phosphate with the total concentration of 100 mM. The solution is to be prepared in DI water and the pKa value
  2. Biochemistry

    How would you prepare 250ml of 0.2M sodium phosphate buffer of PH 6.4 if the following chemicals are available :dibasic sodium phosphate,monobasic sodium phosphate and 0.129M solution of NaOH. Assume that the pka1 pka2 pka3 of
  3. Chemistry--DR.BOB HELP!

    If 1 volume of 0.1 KH2PO4 is mixed with 2 volumes of 0.1 OHEtNH2 (pka=9.44), what will be the pH of the mixture? I know I know: HH equation

  5. chemistry

    describe an alternative method to prepare a 0.2M potassium phosphate buffer using KH2PO4 and KOH
  6. chemistry

    Online chemistry lab preparing standards help? I was told to prepare some standard for a chemistry lab and here where the instructions: Obtain a solution of known phosphate concentration. In this lab we will use (1.e-002M)
  7. chemistry

    does kh2po4 react with sodium lauryl sulphate and can we use nah2po4 insted of kh2po4 in prepration of 0.2 m phosphate buffer ?
  8. chemistry

    if 10.3 lithium sulfate react with an abundant amount of potassium phosphate, what mass of lithium phosphate can you expect to isolate? lithium sulfate to lithium phosphate : 10.03 x 3 li3PO4 x 115.79 Lipo4 / 109.94 liSo4 / 3
  9. Chemistry

    Calculate the pH of a potassium phosphate buffer if the pKa of KH2PO4 is 7.2 and the acid-base ratio is 2:1 I took Chemistry 7 years ago and am in a review for a Biochem course I am takin. I do not remember the basics so any help
  10. BioChem

    1.Suppose you had a buffer containing 0.5 moles of sodium monobasic phosphate and 0.5 moles of sodium dibasic phosphate. How many moles of hydrochloric acid would this phosphate buffer be able to accept before the pH of the

More Similar Questions