Question

A procedure calls for a 250 mM pH 5 acetate buffer. (a) What concentrations of sodium acetate and acetic acid should you use? (b) If the procedure requires 4 L of this buffer solution how many moles and grams of each buffer component will be required? (8 points) 2.

Answer 1

Answer =

2.For preparation of a 250mM ,pH 5 acetate buffer is

a] the concentrations of sodium acetate and acetic acid should use are

the concentrations of sodium acetate = 250 mM

the concentrations of acetic acid = 250 mM.

b] Preparation of 4 liter of acetate buffer is

solution A - 250mM acetic acid

60.05 ml---------------- 1000 ml -----------1 M i.e. 1000 mM

? ml-----------------------1000 ml ---------- 250mM

= 250X 60.05 / 1000

= 15.01 ml

15.01 ml of acetic acid is taken diluted to 1000 with distilled water to make 250mM

Solution 'B' - preparation of 250 mM sodium acetate -

molecular weight of sodium acetate = 82.03

82.03 gms of sodium acetate ------------ 1000 ml of D.water -------- 1 M i.e.1000 mM

? gms of sodium acetate ------------------ 1000 ml of d.water -------- 250 mM

= 82.03 X 250 / 1000

= 20.50 gms of sodium acetate. for 1 liter

therefore for preparation of 4 liter of acetate buffer

82.03 gms of sodium acetate taken then add distilled water to make final volume 4 L.

x ml of 'A' y ml of 'B' adjusted to final volume 4 L.

- for 100 ml 14.8 ml 35.2 ml pH -5

- for 4000 ml 592 ml 1408 ml pH 5

for preparation of 4L of acetate buffer,mix 592 ml 250mM of acetic acid and 1408 ml of 250mM of sodium acetate make a final volume with distilled water.