Analysis of the mass of acetylsalicylic acid (aspirin) in an Aspirin Tablet.

Procedure: Standardization of dilute sulphuric acid 1. 1.32g of the sodium carbonate was weighted accurately in a beaker. 2. 120cm3 of deionised water was added to the beaker containing sodium carbonate. 3. The mixture was stirred gently to let the sodium carbonate to dissolve. 4. The solution was poured into a 250cm3 volumetric flask. 5. The beaker was washed out with further small quantities of water. 6. All the washings were poured into the 250cm3 volumetric flask to ensure no solution …

…of alkaline hydrolysis. The reaction why we need to heat the mixture is that the reaction between them is quite slow, so we need to heat it to increase the reaction rate. In the experiment, we use phenolphthalein as the indicator, however as the alkaline hydrolysis between sodium hydroxide and aspirin will form acetic acid ad salicylic acid, which are 2 weak acids, so that rather than phenolphthalein, using phenol red indicator is much more suitable.