Chemistry

posted by .

You are asked to prepare 500. mL of a 0.150 M acetate buffer at pH 5.00 using only pure acetic acid, 3.00 M NaOH, and water. Calculate the quantities needed for each of the following steps in the buffer preparation.

1. Add acetic acid to ~400 mL of water in a 500 mL beaker. How many grams of acetic acid do you need?

2. Add 3.00 M NaOH solution while stirring and monitoring the pH with a pH electrode until the pH is 5.00. What volume of NaOH solution do you calculate that you will need?

By taking the desired moles of the solution (0.15M x 0.5L = 0.075 moles), I was able to calculate the needed Acetic Acid (Question #1 = 4.5g)

(Desired Moles) 0.075 x (Formula Weight) 60.05 = 4.5g Acetic Acid.

Where I am stuck is Question 2. After using HH:

(AC/HAC)=10^(5-4.76), (AC/HAC)=1.74

After this, I multiplied my HAC (0.075) by my 1.74 to achieve my AC (0.13).

I know I need to incorporate this with my Molarity of base (3.00M), but am not sure how. Am I even on the right track?

Thank you very much in advance.

  • Chemistry -

    You want 0.075 mols to start HAc. You're right there (and the 4.50 g is correct).
    5.00 = 4.75 + log (b/a)
    b/a = 1.82 or
    b = 1.82*a or
    a = 0.549*b. Substitute this into the below for a.

    b+ a = 0.15 x 0.5 = 0.075 mols.
    b + 0.549b = 0.075
    1.549b = 0.075
    b = 0.0484 mols.
    3.0M = 0.0484 mols/L
    and L = 0.0161 L or 16.1 mL.
    Check my arithmetic.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. college chem

    a. According to the Henderson-Hasselbalch equation, how many grams of sodium acetate will you need to add to 125 mL of 0.100 M acetic acid to make a pH=4.74 buffer?
  2. CHEMISTRY HELP!

    a. According to the Henderson-Hasselbalch equation, how many grams of sodium acetate will you need to add to 125 mL of 0.100 M acetic acid to make a pH=4.74 buffer?
  3. chemistry

    Prepare 500mL of a 0.200 M acetate buffer at pH 4.90 using only pure acetic acid, 3M NaOH, and water. 1) Add acetic acid to ~400mL of water in a 500 mL beaker. How many grams of acetic acid are needed?
  4. school

    What is the pH of 0.1 M formic acid solution?
  5. Chemistry

    You are preparing 500 mL of a 0.300 M acetate buffer at pH 4.60 using only sodium acetate, 3.00 M HCl, 3.00 M NaOH, and water. Calculate the quantities needed for each of the following steps in the buffer preparation. 1. Add sodium …
  6. Chemistry

    You want to prepare a pH=4.50 buffer using sodium acetate and glacial acetic acid. You have on hand 300 mL of 0.100 M sodium acetate. How many grams of glacial (water free) acetic acid should you add to prepare the buffer?
  7. Chemistry

    If you need to prepare 250.0 mL of a pH 5.00 buffer that has a total buffer concentration of acetic acid + sodium acetate of 0.050M, how many moles of each will you need to prepare the solution?
  8. Quantitive Analysis

    You are asked to prepare 500. mL of a 0.250 M acetate buffer at pH 4.90 using only pure acetic acid (MW=60.05 g/mol, pKa=4.76), 3.00 M NaOH, and water. Answer the following questions regarding the preparation of the buffer. Question …
  9. CHEMISTRY

    Calculate the amount (in mL) of 1.520M NaOH that is required to add the following acetic acid solution to prepare a buffer with the corresponding pH: 30.00mL of a 5.00% (w/v%) acetic acid; the resulting acetate buffer has a pH of 5.75. …
  10. Chemistry: Buffer Intensity problem

    You wish to prepare a pH 4.76 acetic acid sodium acetate buffer with a buffer intensity of 1 M per pH. What concentrations of acetic acid and sodium acetate are needed?

More Similar Questions