Thermodynamics in Bioenergetics

Jean-Louis Burgot

• Publisher: CRC Press
• Year: 2019
• eBook ISBN: 9781351034203
• Topic: Medicine
• Subtopic: Biochemistry in Medicine

Thermodynamics in Bioenergetics aims to supply students with the knowledge and understanding of the critical concepts and theories that are needed in the biochemistry and bioenergetics fields. Biochemical reactions highlighting thermodynamics, chemical kinetics, and enzymes are addressed in the text. Author, Jean-Louis Burgot, guides the reader through the starting points, strategy description, and theory results to facilitate their comprehension of the theories and examples being discussed in the book. Also discussed in the text are the notions of Gibbs energy, entropy, and exergonic and endergonic reactions.

Part I

Fundamentals of Classical Thermodynamics

Chapter 1

Some Recallings of Physics

This first chapter is devoted to some recallings of physics, especially to the notions of pressure, work, heat and temperature since they are recurrent in thermodynamics. Although the methods of classical thermodynamics are independent of any theory concerning the existence of atoms and of molecules, it is now well-admitted that some kind of work, pressure and temperature are manifestations of the movements of these “particles”. This is the reason why these notions are tackled now.

1) An approach to a perfect gas

A fluid, defined as being a perfect gas, is an hypothetical one, the properties of which are:

– its structure is discontinuous. It is constituted of independent particules (atoms and molecules) which may be considered as “point-particules” but which, however, are endowed with the mass m;

– all its molecules are moving;

– all the collisions of its molecules with the walls of their container are elastic;

– there exists no “interaction” between the particules. Only the contact-forces developing during the impacts exist;

– it contains a huge number of particules, whatever the volume of the container is. This is the reason why statistical methods must be used to grasp classical thermodynamics in more detail. This is the objective of statistical thermodynamics.

These hypotheses imply that the perfect gas molecules only possess a kinetic energy because they are moving, possess no energy of another kind and there are no interactions between them. Defining the system under study as being constituted by the whole gases, its internal energy U is only of kinetic kind.

Actually, a perfect gas is only a theoretical model. However, the behavior of a dilute gas tends to be that of a perfect gas. This is because, then, the average distance between the molecules is great with respect to the range of interactions due to the intermolecular forces.

The conclusions to which this concept leads are of utmost importance. We shall come back several times to it. The concept of perfect gas is far-reaching.

Exercise 1:

Calculate the number of molecules of a perfect gas present in a container of a volume V = µ³ (1 micrometer power 3) under the normal pressure p = 1 atm at the temperature t = 0°C, knowing that:

– the quantities p,V, T and the number of moles n of the gas are related to each other by the equation of perfect gases (R is a constant named perfect gas constant R = 8,314 J K⁻¹):

$pV=nRT$

– the number of “true” molecules in one mole is the Avogadro number: N_A (N_A = 6,022 10²³). It is known that 1...

Table of contents

• Cover
• Title Page
• Copyright Page
• Preface
• Acknowledgments
• Table of Contents
• Glossary
• Part I: Fundamentals of Classical Thermodynamics
• Part II: Some Aspects of Chemical Reactions in Aqueous Solutions
• Part III: Thermodynamics of Biological Cells
• Appendices
• General Bibliography
• Index