Titration of a Diprotic Acid Lab Steps

The purpose of this experiment is to determine an unknown diprotic acid by examining its molecular weight using titration.


(1) Dissolve 0.120 g of the unknown in 100 mL of distilled water.

(2) Place the 250 mL beaker ontop of a magnetic stir plate, and suspend a pH electrode into the solution using a ring stand.

(3) Fill buret to 0 mL level with sodium hydroxide, prepare computer software.

(4) Wait for pH to stabilize then keep data point and set as zero level.

(5) Add enough NaOH to increase pH by 0.20 and keep data point.

(6)Repeat til pH of solution reaches 3.5, then begin using 2 drop increments til 4.5.

(7) Use 0.20 increments from 4.5-7.5, then continue with 2 drop increments til pH 10

(8) 0.20 increments from 10-11.