chemistry

A buffer is prepared using acetic acid, CH3COOH, (a weak acid, pKa = 4.75) and sodium acetate, CH3COONa (which provides acetate ions, the conjugate base), according to the following proportions:

Volume of CH3COOH(aq): 100.0 mL
Concentration of CH3COOH(aq): 1.151 M

Volume of CH3COONa(aq): 113.0 mL
Concentration of CH3COONa(aq): 1.270 M

Use the Henderson-Hasselbalch equation (below) to calculate the pH of the buffer solution.
pH=pKa+log[A−][HA]

  1. 👍
  2. 👎
  3. 👁
  1. equation is pH=pKa+log[A−]/[HA]?

    1. 👍
    2. 👎
  2. yes

    1. 👍
    2. 👎
  3. Plug in the numbers and calculate it.

    1. 👍
    2. 👎
    👤
    DrBob222
  4. is it just = 4.75+log(1.270/1.151)?

    1. 👍
    2. 👎
  5. Yes, it's just that.

    1. 👍
    2. 👎
    👤
    DrBob222
  6. you dont need to take the volume into consideration?

    1. 👍
    2. 👎
  7. The formula is pH = pKa + log (base)/(acid)/ Concn is in mols/L which is M
    so you substitute the MOLAR CONCENTRATIONS and that's it.

    1. 👍
    2. 👎
    👤
    DrBob222
  8. i see, thanks!

    1. 👍
    2. 👎
  9. i think its this:
    Volume of final solution = (100.0 + 113.0) mL = 213.0 mL

    [CH₃COOH] = (1.151 M) × (100.0/213.0) = 0.5404 M
    [CH₃COO⁻] = (1.270 M) × (113.0/213.0) = 0.6738 M

    Henderson-Hasselbalch equation:
    pH = pKa + log([CH₃COO⁻]/[CH₃COOH])
    pH = 4.75 + log(0.6738/5404)
    pH = 4.85

    1. 👍
    2. 👎
  10. yes, youre right vace

    1. 👍
    2. 👎
  11. I hate to say it but you guys are right and I'm wrong. The volume DOES make a difference although not in a big way. My mistake is this.
    I looked at the divisor of 213 and thought dividing by a common number left concentrations the same so the concentrations would be the same. However, that isn't true since the initial volumes were different. Sorry about that. I just didn't think it through.

    1. 👍
    2. 👎
    👤
    DrBob222
  12. no worries, your help still means a lot!

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Chemistry

    100 mL 0.1 M sodium acetate solution is mixed with 50 mL 0.1 M acetic acid. If now 0.937 mL of 1 M sodium hydroxide is added to the buffer what is the change in pH? pKa (acetic acid) = 4.76

  2. chemistry

    A buffer is prepared using acetic acid, CH3COOH, (a weak acid) and sodium acetate, CH3COONa (which provides acetate ions, the conjugate base), according to the following proportions: Volume of CH3COOH(aq): 131.0 mL Concentration

  3. chemistry

    A. Strong Base 1.) What is the concentration of a solution of KOH for which the pH is 11.89? 2.) What is the pH of a 0.011M solution of Ca(OH)2? B. Weak Acid 1.) The pH of a 0.060M weak monoprotic acid HA is 3.44. Calculate the Ka

  4. Biochemistry

    Calculate how you would make 0.5L of a 0.5M (500mM) acetate buffer at a pH of 4.7. Available is sodium acetate and glacial acetic acid. pH=4.7 pKa of acetic acid=4.76 Not sure if I did this next part right: 4.7=4.76 + log

  1. Science- Chemistry

    How many grams of sodium acetate( molar mass 82.03 g/mol) must me added to 1.00L of a 0.200M acetic acid solution to form a buffer of 4.20?Ka value for aceic acid is 1.8 x 10^-5. How do I go about finding the grams from the given

  2. CHEMISTRY

    HOW CAN U TELL IF HNO3 +KNO3 IS A BUFFER SOLUTION A buffer solution must contain a weak acid and its conjugate base OR a weak base and its conjugate acid. HNO3 is a strong base and KNO3 is the salt of a strong base (KOH) and a

  3. Biochemistry

    Show Calculations used in mkaing 250mL of 0.5M sodium acetate ph 4.7. You are given: 1M acetic acid (weak acid) 1M sodium hydroxide (strong base) Sodium acetate buffer: ph 4.7 acetic acid pKa: 4.7 So far this is what I've gotten:

  4. 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)

  1. organic chem

    . Use the Henderson-Hasselbach equation: pH = pKa + log [A-]/[AH], where A- is the conjugate base and AH is the weak acid. Calculate the pH of an acetate buffer in which the acetate concentration [CH3COO-] is 3.5 times greater

  2. Chemistry

    1. Calculate the pH of a buffer solution that contains 0.32 M benzoic acid (C6H5CO2H) and 0.17 M sodium benzoate (C6H5COONa). [Ka = 6.5 × 10-5 for benzoic acid] Round your answer to two places past the decimal. 2. A solution is

  3. Chemistry 122

    A solution is prepared to be 0.10 M acetic acid, HC2H3O2, and 0.20 M sodium acetate, NaC2H3O2. What is the pH of this buffer? Ka for acetic acid is 1.7 x 10^-5. What is the pH after 9.5 mL of 0.10 M hydrochloric acid is added?

  4. chem equilibrium

    Determine the pH of a buffer that is prepared by mixing 100 mL of 0.2 M NaOH and 150 mL of 0.4 M acetic acid assuming the volume is additive. Calculate the pH of the solution when 0.5 mL of 1 M of HCl was added hence calculate the

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