Physical Chemistry of Foods
only apparent, of the reaction: see Section 4.4. Also the rate constant is an empirical quantity to be experimentally determined ...
Note Up till now, we have used concentrations in the rate equations, whereas we have learned in Chapter 2 that activities should ...
different from those in a heat exchanger, for instance the times needed for heating up and for cooling may differ. (c) Occasiona ...
first is due to changes in solvation; its quantity is rarely of the order of magnitude of a covalent bond energy. The second is ...
large, it may take a long time before a significant relative decrease in [A] occurs. Consequently, we have an approximate steady ...
This clearly asks for an explanation, and an attempt will be made below. To that end it is useful first to say something about t ...
any mechanical external energy applied to them, say due to streaming of a liquid. This is illustrated when we calculate the aver ...
as well, thereby traveling over some distance (Brownian motion); in vapor (or air) the molecules travel over far larger distance ...
preexponential factor and denoted ask?ork 0 , i.e., the value thatkwould attain at infinite temperature or zero activation energ ...
slightest force is applied). In this case, the Arrhenius type relation directly derives from the Maxwell–Boltzmann distribution. ...
energy. The great advantage of the Eyring theory is the introduction of the activation entropy, which may be considerable in man ...
entropy (this is further discussed in Section 7.2). Consequently, the reaction can proceed despite the very large activation ent ...
microbes (as well as microbial spores). Inactivation kinetics of enzymes is often determined by the unfolding kinetics of globul ...
Question In a study on heat inactivation of a peroxidase enzyme (EC 1.11.1.7), it was found that 5 min heating at 72 8 C left 55 ...
encounter frequency. The basic theory is due toSmoluchowski: it gives the encounter rate of diffusing particles or molecules, as ...
of 10^3 Pa?s is not exceptional in a low-moisture food, Eq. (4.16) would yield 7? 103 , and then the reaction may still be diffu ...
The absolute rate theory implicitly assumes that the addition of a given amount of free energyðDG{Þwould be sufficient for a rea ...
Order and Molecularity. If we have a very simple reaction, like HþH?H 2 in the gas phase, this is a true bimolecular reaction an ...
other hand,k 15 k 2 , any U that is formed will almost immediately be converted into I, and½U&0, again leading to a simple ...
enthalpy. A small apparent activation energy may result if the first of two consecutive elementary reactions is in fact reversib ...
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