Keywords
Henderson-Hasselbalch equation
Experimental limits
Buffer dilution
Buffer index
Multiple buffers
Ionic strength
Preparation of buffers
How to Cite
Abstract
Chemical and biochemical processes can be significantly altered by small variations in the pH of the medium, so that many experimental studies require effective means to control this parameter. There are mechanisms that allow the pH control of aqueous solutions when adding (small) amounts of strong acids or strong bases to the chemical system. These solutions, known as buffer [1], are composed of a mixture of a weak acid salt with a strong base and its respective weak acid (eg sodium acetate / acetic acid) or a weak base salt with acid strong and its respective weak base (eg ammonium chloride / ammonia). The concept of a buffer was proposed in the early twentieth century and has been studied ever since. Note that the main purpose of a buffer is to control the pH of the solution, but it can also perform secondary functions, such as controlling the ionic strength of the reaction medium. According to the theory proposed by Brønsted and Lowry [2-5], they should be seen only as mixtures of conjugated acids and bases that minimize the pH variations of an aqueous solution through the effect of the common ion. This text hopes to give a broader and more critical view of acid-base buffers
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Silva CR, Simoni JA. Avaliação da capacidade tamponante - um experimento participativo. Química Nova, 2000, 23: 405-409.
Buckley PT. Preparation of buffers: an experiment for quantitative analysis laboratory. J. Chem. Educ., 2001, 78: 1384.
Pergantis SA, Saridakis I, Lyratzakis A, Mavroudakis L, Montagnon T. Buffer squares: a graphical approach for the determination of buffer pH using logarithmic concentration diagrams. J. Chem. Educ. 2019, 96: 936−943.
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