Heterogeneous or heterogeneous systems
In chemistry and physics, as well as a number of other sciencesvarious terms are used to designate a particular system. This is necessary for making necessary classifications and simplifying the study of specific processes. Heterogeneous systems in the literal sense of the system are heterogeneous, although they consist of homogeneous parts. In this issue, there are a number of features that can make it difficult to understand these processes.
As we know, matter can exist in different states. And between these states is a very significant difference, which ultimately even affects the properties.
The most common heterogeneous systems area liquid that can pass into a saturated solution or vapor, many alloys, etc. Two basic states of matter are distinguished: crystalline and amorphous. They largely determine certain physical, thermodynamic and other properties.
In heterogeneous systems, variousdiscontinuities in the continuity of physical properties. Scientists call them interface surfaces, which, as a rule, are fairly easy to determine. If the external conditions change, these sections can also shift to one side or the other, which eventually leads to changes in all properties. Equilibrium in heterogeneous systems is very important if it is necessary to maintain one state throughout the entire reaction or experiment.
Heterogeneous reactions
Speaking of such systems, we can not fail to mentionthose areas of work where they are applied. Heterogeneous reactions are reactions occurring in heterogeneous systems, i.e. it involves substances that are in different phases. This is a full-fledged heterogeneous system.
Examples of reactions may be dissolutionmetals in acids, the decomposition of salts with the formation of solid and gaseous products and some others. Also included here are some catalytic reactions that occur on the surface of the catalyst. The main feature of such heterogeneous catalytic reactions is that the reagent and the released products can be in different states.
The phase difference as a whole makes it difficult to work with datareactions, because the transport of substances, mixing and diffusion is complicated, and the activation of molecules can begin even at the stage of entry to the interface.
For the reaction to take place, a constantReplenishment of reagents and removal from the area of products formed as a result of the chemical process. In this case, the reaction kinetics or the percolation rate are determined by specific substances, the rate of the chemical transformation itself, and the properties that heterogeneous systems possess. If no difficulties arise, and the diffusion of substances is maintained in the normal state, then the reaction rate is proportional to the size of the zone. This is the so-called specific reaction rate. In this case, the concentration, reaction conditions, partial pressures, and so on are taken into account. The ratio of thermodynamic activities, produced products and starting materials determines the equilibrium constant of the heterogeneous system.
This constant is necessary for the calculationpractically any reactions in dissimilar systems. With its help it will be possible to accurately determine the amount of initial substances necessary for a full-fledged chemical reaction, and it will also be possible to calculate the exact yield of the products. When operating with such data, the reaction is easily controlled, in addition, the direction of the reaction can always be controlled. In connection with this, we can say that the equilibrium constant is extremely important for carrying out reactions in heterogeneous systems.
