Design and preparation of buffers effective at different pHs
Experiment 1 : Design and preparation of buffers effective at different pHs
Abstract
The body uses natural buffers to maintain the many different pH environments in our body. This is important for optimum activity of our enzymes. When doing experiments in vitro using these enzymes it is important to mimic intracellular conditions using artificial buffer systems in order to obtain accurate results. In this experiment the buffering properties of three artificial buffer systems containing acetic acid, Gylcine and Tris were investigated. Overall the pKa values obtained experimentally were similar to the published pKa values and the range of the buffer systems were roughly ± 1 pH unit from the pKa values.
Introduction
A buffer solution works to minimise the change in pH on addition of acid or alkali. Different buffer systems are effective over different pH ranges. The aim of this experiment is to investigate the ranges at which three different buffer systems: Acetic acid/NaOH, Tris/HCl and Gylcine/NaOH are effective.
Materials and Methods
Three titrations were carried out: Acetic acid/NaOH, Tris/HCl and Gylcine/NaOH. 25ml of the weak acid or weak base was put into a beaker and its pH measured. Then it was titrated with the strong acid or strong base respectively while measuring the pH of the buffer (using a pH probe) on addition of every 1 ml of acid or base from the burette. Two point calibration was carried out prior to each titration using the three calibration solutions of pH 4, 7 and 9.2; for the Acetic acid/NaOH the calibration solutions used were: 4 and 7, for the Tris/HCl and for the Gylcine/NaOH the solutions used were 7 and 9.2. When carrying out the titration plot a rough graph in real time to immediately highlight any anomalies. For comparison carry out a similar experiment with strong acid and strong base where the acid is in the beaker and base is in the burette.
To make 0.1 M solution of Gylcine dissolve 0.75 g of Gylcine in 100 ml of
Abstract
The body uses natural buffers to maintain the many different pH environments in our body. This is important for optimum activity of our enzymes. When doing experiments in vitro using these enzymes it is important to mimic intracellular conditions using artificial buffer systems in order to obtain accurate results. In this experiment the buffering properties of three artificial buffer systems containing acetic acid, Gylcine and Tris were investigated. Overall the pKa values obtained experimentally were similar to the published pKa values and the range of the buffer systems were roughly ± 1 pH unit from the pKa values.
Introduction
A buffer solution works to minimise the change in pH on addition of acid or alkali. Different buffer systems are effective over different pH ranges. The aim of this experiment is to investigate the ranges at which three different buffer systems: Acetic acid/NaOH, Tris/HCl and Gylcine/NaOH are effective.
Materials and Methods
Three titrations were carried out: Acetic acid/NaOH, Tris/HCl and Gylcine/NaOH. 25ml of the weak acid or weak base was put into a beaker and its pH measured. Then it was titrated with the strong acid or strong base respectively while measuring the pH of the buffer (using a pH probe) on addition of every 1 ml of acid or base from the burette. Two point calibration was carried out prior to each titration using the three calibration solutions of pH 4, 7 and 9.2; for the Acetic acid/NaOH the calibration solutions used were: 4 and 7, for the Tris/HCl and for the Gylcine/NaOH the solutions used were 7 and 9.2. When carrying out the titration plot a rough graph in real time to immediately highlight any anomalies. For comparison carry out a similar experiment with strong acid and strong base where the acid is in the beaker and base is in the burette.
To make 0.1 M solution of Gylcine dissolve 0.75 g of Gylcine in 100 ml of