Sunday 17 March 2013

Acid - Base Titration Experiment


Title : Acid Base Titration

Abstract : By using acid-base titration, we determine the pH of a certain solution which we used weak acids in this experiment. The titrations were carrying out by titrating acetic acid, phosphoric acid and amino glycine acid with sodium hydroxide (NaOH), the base. For each titration, we record its pH using pH meter. Then, the data collected were derived into graph and analyze it by determine its pKa value, inflection and equivalent point based on “Henderson-Hasselbalch” equation. The graphs were compared between those three weak acids.

Introduction : Acid-base reactions are one of the important chemical interactions. They are vital to both environmental and industrial systems. It is known for its important variable, pH, controls toxicity, mobility, solubility and aquatic ecosystem. A titration is an analytical technique that allows the quantitative determination of a dissolved substance being titrated which known as an analyte. In a titration of a weak acid with strong base the titrant, involves the direct transfer of protons from the weak acid to the hydoxide ion (OH-).  The titration curve is a graph of the volume of titrant, or in our case the volume of strong base, plotted against the pH.
Equation involve: Henderson-Hasselbalch equation

pH = pKa + log ( [conjugate base] / [acid]) )



Materias and apparatus :


·   25ml of 0.1M acetic acid
·   25ml of 0.1M phosphoric acid
·   25ml of 0.1M amino glycine acid
·   0.1M NaOH
·   Calibrated pH meter
·   Burette
·   Conical flask
·   Filter funnel
·   Measuring Cylinder

Methodology :











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