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Name: Supervisor: Course: Date: PH and Buffer PURPOSE The purpose of this experiment is to use the Henderson-Hasselbach equation to prepare buffers of known PH and composition. The exercise also seeks to compare and predict observed pH of buffers prepared. This laboratory exercise also aims at using pH electrode during titration of sodium phosphate in order to obtain an acid-base titration curve. It also involves calculating the pKa value of a buffer from its titration curve (Chem354 Biochemistry Notes, 6). MATERIALS AND METHODS Materials. They include a stirring plate, a digital pH meter, magnetic stirring bars, a clamp for pH sensor, Standard pH solutions at 4, 7 and 10, sodium acetate and glacial acetic acid. It also requires a wash bottle with distilled water, pipet and pipet aid, plastic waste beaker, and a p-1000 adjustable micro-pipette. Methods Preparing a 0.2m sodium acetate and 0.2M acetic acid stock solutions. The first part of the involved preparing a 250 mL of 0.2M sodium acetate. This was done by adding distilled water (200mL), dissolving and stirring. The next step was preparing 400mL of 0.2M of acetic acid with a molar weight of 60.1g/mol. Glacial acetic acid was added into distilled water (300mL) followed by stirring. Preparation of acetic buffers. It involved preparation of 0.2M acetic buffer at pH 4 from 0.2M acetic acid and 0.2M sodium acetate. The solution was prepared in a beaker and a pH meter was used to measure the mass of the acetic buffer after calibrating the pH electrode. The predicted and observed pH were recorded in a table. The next step involved preparation of 0.2M acetate buffer by mixing 70mL of 0.2M sodium acetate and
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