Thermodynamics and Chemical Kinetics of Living Systems

Calorimeters are instruments used for the direct measurement of heat quantities including heat production rates and heat capacities. Different measurement principles are employed and a very large number of calorimetric designs have been described since the first calorimetric experiments were reported more than 200 years ago. The amount of heat evolved in a chemical reaction is proportional to the amount of material taking part in the reaction and the heat production rate the thermal power, is proportional to the rate of the reaction. Calorimeters can therefore be employed as quantitative analytical instruments and in kinetic investigations, in addition to their use as thermodynamic instruments. Important uses of calorimeters in the medical field are at present in research on the biochemical level and in studies of living cellular systems. Such investigations are often linked to clinical applications but, so far, calorimetric techniques have hardly reached a state where one may call them clinical (analytical) instruments. ... 

Chemical reactions in living systems involve orderly release, storage, or utilization of energy. Knowledge of thermodynamics and kinetics is essential to appreciate how this occurs. Thermodynamics deals with the changes in energy content between reactants and products, whereas kinetics is concerned with the reaction rates. 

There s another example of water-in-oil compartmentation, which can circumvent this problem water-in-oil emulsions. These can be prepared by adding to the oil a small amount of aqueous surfactant solution, with the formation of more or less spherical aggregates (water bubbles) having dimensions in the range of 20-100 p,m in diameter. These systems are generally not thermodynamically stable, and tend to de-nfix with time. However, they can be long-lived enough to permit the observation of chemical reactions and a kinetic study. 

Like catalysis itself, asymmetric catalysis is fundamentally a kinetic phenomenon. It has some important consequences. The intermediate complexes that can be detected spectroscopically may not be directly involved in the catalysis. It is also true for the thermodynamically favored catalyst-substrate complexes that are not always responsible for the chemical transformation of the substrate. The catalytically active species are often short lived and are present in very low concentration in the catal3d ic system. 

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