Chemistry

A buffer is prepared by adding 0.97 L of 1.1 M HCl to 805 mL of 1.7 M NaHCOO. What is the pH of this buffer? [Ka(HCOOH) = 1.7 × 10-4]

  1. 👍 0
  2. 👎 0
  3. 👁 204
  1. Use the Henderson-Hasselbalch equation. Post your work if you get stuck.

    1. 👍 0
    2. 👎 0
  2. What I did the first time:
    pH = -log(1.7*10^-4) + log (1.7/1.1)

    I tried it this way before, but it said I got the wrong answer. Does it have something to do with the Ka value?

    1. 👍 0
    2. 👎 0
  3. No. You substituted molarity of the individual solutions BEFORE they were mixed. After mixing the molarity has changed.
    initial CH3COO^- = 1.7M x 0.805L =1.3685 moles.
    initial HCl = 1.1M x 0.97 L = 1.067 moles.
    ............CH3COO^- + H^+ ==> CH3COOH
    initial mols.1.3685...1.067.....0
    change.....-1.067.....-1.067.....1.067
    final.......0.3015.....0........1.067

    final (CH3COO^-) = 0.3015/total volume.
    final (CH3COOH) = 1.067/total volume.
    Those are the numbers you substitute into the HH equation.

    1. 👍 0
    2. 👎 0
  4. total volume = 1.775 L

    final concentration (CH3COO)= .169859
    final concentration (CH3COOH) = .60112676

    pH= -log(1.7*10^-4) + log(.169859/.60112676)

    = 3.22

    is this correct?

    1. 👍 0
    2. 👎 0
  5. 1.775 is right.
    Concn CH3COO is right.
    Concn CH3COOH is right.
    Your answer of 3.22 is correct for the value of Ka you show in the problem of 1.7 x 10^-4; however, you may want to check your post and the problem from which you copied it because the Ka for CH3COOH (acetic acid) is 1.7 x 10^-5 (not 10^-4) so the correct answer for your post is 3.22 but the correct answer for an acetic acid/acetate buffer in that proportion is 4.22.

    1. 👍 0
    2. 👎 0
  6. ok thanks!

    1. 👍 0
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. Chemistry

    Buffer capacity is a measure of a buffer solution\'s resistance to changes in pH as strong acid or base is added. Suppose that you have 165 mL of a buffer that is 0.360 M in both benzoic acid (C6H5COOH) and its conjugate base

  2. Chemistry (buffers)

    Say, for example, that you had prepared a Buffer C, in which you mixed 8.203 g of sodium acetate, NaC2H3O2, with 100.0 mL of 1.0 M acetic acid. a. What would be the initial pH of Buffer C? HOW???????

  3. school

    What is the pH of 0.1 M formic acid solution? Ka=1.7„e10-4? What is the pH value of buffer prepared by adding 60 ml of 0.1 M CH3COOH to 40 ml of a solution of 0.1 M CH3COONa? What is the pH value of an acetate buffer (pK=4.76)

  4. Chemistry

    1)A buffer solution that is 0.10 M sodium acetate and 0.20 M acetic acid is prepared. Calculate the initial pH of this solution. The Ka for CH3COOH is 1.8 x 10-5 M. As usual, report pH to 2 decimal places. *A buffered solution

  1. chemistry

    Select only the True statements about buffer systems. Select all that are True. 1. Starting with NH3(aq) and adding a small amount of HCl(aq) will make a buffered solution. 2. The blood buffer, among other things, is supported by

  2. Chemistry

    How would you calculate the pH of the buffer if 1.0mL of 5.0M NaOH is added to 20.0mL of this buffer? Can someone please explain to me how to do B and C step by step so I could understand it clearly? :) Say, for example, that you

  3. Chemistry

    A buffer is prepared by mixing 45.0 mL of 0.15 M NaF to 35.0 mL of 0.10 M HF (Ka = 6.8x10^-4) Calculate the pH of this buffer after 5.0 mL of 0.05 M HCl is added.

  4. chem 2

    A buffer is prepared by adding 300.0mL of 2.0M NaOH to 500.0mL of 2.0M CH3COOH. What is the pH of this buffer? ka=1.8x10-5

  1. Chemistry(Please check)

    Which of the following mixtures will be a buffer when dissolved in 1 liter of water? 0.10 mol Ba(OH)2 and 0.20 mol HCl 0.30 mol KCl and 0.30 mol HCl 0.40 mol NH3 and 0.40 mol HCl 0.20 mol HNO2 and 0.10 mol NaOH 0.20 mol HBr and

  2. Biochemistry

    A buffer solution is prepared by mixing 2.50 mL of 2.00M sodium acetate with 3.30mL of 0.500M HCl and diluting the buffer with water to a final volume of 500.0mL. pK acetic acid: 4.76 what is ph of buffer? what is final

  3. chem

    The pH of the nitrite buffer has changed from 3.00 to 2.80 by adding 11.0mL of 12.0M HCL. How many grams of solid sodium Hydroxide would the chemist add to the buffer to change the pH from 3.00 to 3.80?

  4. Chemistry

    One liter of a 0.1 M Tris buffer (pKa of Tris = 8.3, ) is prepared and adjusted to a pH of 2.0. [HA] = 0.10 and [A-] = 5.012E-8 What is the pH when 1.5 mL of 3.0 M HCl is added to 1.0 L of the buffer?

You can view more similar questions or ask a new question.