Effect Of Temperature On The Alkaline Hydrolysis Of Aspirin.docx

Effect of temperature on the alkaline hydrolysis of Aspirin Aspirin follow first order rate kinetics Log Ct = log Co – (Kt/2.303) slope = - (K/2.303)

, K = slope x – 2.303

Procedure: 1. 2. 3. 4.

In a dry volumetric flask place 50 ml of 50 % sodium citrate solution. Place the flask in a constant temperature water bath adjusted at 70 oc. When the solution reaches the temperature, dissolve 1 gm of the sample. After complete dissolving of the sample, remove 5 ml sample at 0, 5, 10, 20, 30, 45 minutes. The samples are then added to 30 ml water and titrated against N/10 NaOH using phenolphthalein as an indicator.

Calculation:     

Aspirin remaining at any time (t): Ct = 2x-y % aspirin remaining: Ct% = (2x-y) * 100 X X: E.P. at zero time Y: E.P. at time t Plot log Ct% versus time and calculate K time 0 10 20 30 45 60

E.P.

Ct

Ct%

Log Ct%