Chemistry

You have to prepare a pH 3.50 buffer, and you have the following 0.10M solutions available HCOOH, CH3COOH, H3PO4,CHOONa, CH3COONa, and NaH2PO4.
a) What solutions would you use?
b) How many milliliters of each solution would you use to make approximately 1 liter of the buffer?

I figured out the solutions you would use based on the pKa values. The solutions you would use would be CHOOH and CHOONa.

Im stuck on how to find the milliliters of each solution. I used the Henderson-Hasselbalch equation to find the ratio between CHOO- and CHOOH and that is .575 but I'm confused on where to go from there.

  1. 👍
  2. 👎
  3. 👁
  1. It would help if you gave the values of Ka when problems like this is posted. Since Ka values differ from text to text (and from website to website) we can't get the same answer you get if we don't use the same numbers you have. Anyway, I took your 0.575 and calculated that you used 3.74 for pKa formic acid.
    Don't you have a strength of the buffer. 1L of 0.1M buffer; 1 L of 0.3M buffer, or what.

    1. 👍
    2. 👎
  2. If you don't care what the strength of the buffer is you can do it this way. Then when you finish you can calculate the strength of the solution you have prepared.
    let x = mL base; then 1000-x = mL acid.
    3.5 = 3.74 + log (0.1x)/[(0.1)(1000-x)]
    Then solve for x and 1000-x.
    If I punched in the right numbers I get approx 400 mL base and 600 mL acid. You can get a better number when you work the problem. I always like to check thse things.
    pH = 3.74 + log (400/600)
    pH = about 3.56 which is close. Remember that 400 and 600 are just estimates. I think you will come out with 3.5 when you do it right.
    Then you can calculate the M of the final solution.
    You have 0.1 x apprx 400 = approx 40 millimols base and approx 60 mmols acid which makes approx 100 mmols in 1000 mL or 0.1M for the mixture. Again, that isn't exact but you see how to do it from this. In fact, whatever numbers you get the concn will be 0.1M doing it this way.

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. chemistry

    use the Henderson-Hasselbalch equation to calculate the pH of a buffer solution prepared by mixing equal volumes of 0.20 M NaHCO3 and 0.10M Na2CO3.(Ka=5.6x10^-11). how would you prepare NaHCO3-Na2CO3 buffer solution that has the

  2. Chem 2

    Which of the following has the highest buffer capacity? A. 0.10M H2PO4-/0.10M HPO4 2- B. 0.50M H2PO4-/0.10M HPO4 2- C. 0.10M H2PO4-/0.50M HPO4 2- D. 0.50M H2PO4-/0.50M HPOr 2- E. They all have the same buffer capacity. Double

  3. chemistry

    Which of the following pairs can be used to prepare a buffer? (select all that can apply) a. HCl/NaCl b. HF/KF c. NH3/NH4Cl d. HNO3/HNO2 e. NaNO2/HNO3 can you also please explain how they form a buffer? thank you

  4. chemistry

    If you add 5.0 mL of 0.50 M NaOH solution to 20.0 mL to Buffer C, what is the change in pH of the buffer? (where buffer C is 8.203 g sodium acetate with 100.0 mL of 1.0 M acetic acid) I have calculated the pH of buffer C to be

  1. chemistry

    Of the following solutions, which has the greatest buffering capacity? A) 0.821 M HF and 0.909 M NaF B) They are all buffer solutions and would all have the same capacity. C) 0.100 M HF and 0.217 M NaF D) 0.121 M HF and 0.667 M

  2. Chemistry

    A chemist needs to prepare a buffer solution of pH 8.80. What molarity of NH3 (pKb = 4.75) is required to produce the buffer solution if the (NH4)2SO4 in the solution is 1.8 M?

  3. chem 2

    a buffer is to be prepared by adding solid sodium acetate to 0.10M CH3COOH. Which othe following concentrations of sodium acetate will produce the most effective buffer? A. 3.0M CH3COONa B 2.5M CH3COONa C 2.0M CH3COONa D 1.5M

  4. Chemistry

    What is the final pH of the second dilution after adding 1 drop of 0.1 M NaOH? There were 2 ml of buffer per well Calculate the final pH of the undiluted buffer after 0.25 ml of 0.1M NaOH is added. The Ka of CH3 COOH = 1.8 x 10

  1. chemistry

    You have to prepare a pH 5.00 buffer, and you have the following 0.10M solutions available: HCOOH, HCOONa, CH3COOH, CH3COONa, HCN, and NaCN. Which solutions would you use? HCOOH HCOONa CH3COOH CH3COONa HCN NaCN

  2. Chem Lab

    Can the NH3/NH4Cl system be sued to prepare a buffer of a pH 9.5? why or why not? Can it prepare a buffer of pH 5? There were two buffers, 0.2 M and 0.1M.

  3. chemistry

    In protein precipitation, two liters of 5mM buffer solution with pH 5.2 is needed in the isolation of albumin. Which among the buffer solutions is best fitted for the said purpose?justify your answer. a. acetate buffer with

  4. chemistry

    Using 0.1M phosphate buffer, pH 7.2, prepare 25ml each of the buffer solutions with the following concentrations at pH 7.2: 1. 0.005M 2. 0.05M 3. 0.010M

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