Analytical chemistry is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials. Qualitative analysis gives an indication of the identity of the chemical species in the sample, and quantitative analysis determines the amount of certain components in the substance. The separation of components is often performed prior to analysis.
Analytical methods can be separated into classical and instrumental. Classical methods (also known as wet chemistry methods) use separations such as precipitation, extraction, and distillation and qualitative analysis by color, odor, or melting point. Quantitative analysis is achieved by measurement of weight or volume. Instrumental methods use an apparatus to measure physical quantities of the analyte such as light absorption, fluorescence, or conductivity. The separation of materials is accomplished using chromatography, electrophoresis or Field Flow Fractionation methods.
In chemical engineering and related fields, a unit operation is a basic step in a process. Unit operations involve bringing a physical change such as separation, crystallization, evaporation, filtration etc. For example, in milk processing, homogenization, pasteurization, chilling, and packaging are each unit operations which are connected to create the overall process. A process may have many unit operations to obtain the desired product.
Historically, the different chemical industries were regarded as different industrial processes and with different principles. Arthur Dehon Little propounded the concept of "unit operations" to explain industrial chemistry processes in 1916. In 1923, William H.Walker, Warren K. Lewis and William H. McAdams wrote the book The Principles of Chemical Engineering and explained the variety of chemical industries have processes which follow the same physical laws. They summed-up these similar processes into unit operations. Each unit operation follows the same physical laws and may be used in all chemical industries. The unit operations form the fundamental principles of chemical engineering.
A laboratory (// or //; informally, lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed.
Labs used for scientific research take many forms because of the differing requirements of specialists in the various fields of science. A physics lab might contain a particle accelerator or vacuum chamber, while a metallurgy lab could have apparatus for casting or refining metals or for testing their strength. A chemist or biologist might use a wet laboratory, while a psychologist's lab might be a room with one-way mirrors and hidden cameras in which to observe behavior. In some laboratories, such as those commonly used by computer scientists, computers (sometimes supercomputers) are used for either simulations or the analysis of data collected elsewhere. Scientists in other fields will use still other types of laboratories. Engineers use labs as well.
Homogeneity and Heterogeneity are concepts relating to the uniformity in a substance. A material that is homogeneous is uniform in composition or character; one that is heterogeneous is distinctly nonuniform in one of these qualities.
The concepts are the same to every level of complexity, from atoms to populations of animals or people, and galaxies]clarification needed[. Hence, an element may be homogeneous on a larger scale, compared to being heterogeneous on a smaller scale. This is known as an effective medium approach, or effective medium approximations.
In chemistry and chemical engineering, a separation process, or simply a separation, is any mass transfer process that contain a mixture of substances into two or more distinct product mixtures, at least one of which is enriched in one or more of the mixture's constituents. In some cases, a separation may fully divide the mixture into its pure constituents. Separations are carried out based on differences in chemical properties, or physical properties such as size, shape, mass, density, or chemical affinity between the constituents of a mixture, and are often classified according to the particular differences they use to achieve separation. In the case that no single difference can be used to accomplish a desired separation, multiple processes will often be performed in combination to achieve the desired end.
Barring a few exceptions, almost every element or compound is naturally found in an impure state. Often these impure raw materials must be separated into their purified components after they can be put to productive use, making separation processes essential for the modern industrial economy. In some cases these separations require total purification, as in the electrolysis refining of bauxite ore for aluminum metal, but a good example of an incomplete separation process is oil refining. Crude oil occurs naturally as a mixture of various hydrocarbons and impurities. The refining process splits this mixture into other, more valuable mixtures such as natural gas, gasoline and chemical feedstocks, none of which are pure substances, but each of which must be separated from the raw crude. In both of these cases a series of separations is necessary to obtain the desired end products. In the case of oil refining, crude is subjected to a long series of individual distillation steps, each of which produces a different product or intermediate.
In chemistry, phase-boundary catalysis (PBC) is a type of heterogeneous catalytic system which facilitates the chemical reaction of a particular chemical component in immiscible phase react on a catalytic active site located at phase boundary. The chemical component is soluble in one phase but insoluble in the other. The catalyst for PBC has been designed in which the external part of the zeolite is hydrophobic, internally it is usually hydrophilic, notwithstanding to polar nature of some reactants. In this sense, the medium environment in this system is close to that of an enzyme. The major difference between this system and enzyme is lattice flexibility. The lattice of zeolite is rigid, whereas the enzyme is flexible.
Figure 1 shows schematic representation of design of phase-boundary catalytic (PBC) system and its comparison with conventional catalytic system. The PBC is useful primarily for performing reaction at the interface of aqueous phase and organic substrate phases. PBC is needed because the immiscibility of aqueous phase and organic substrate. The name phase-boundary catalysis does what it says; the catalyst acts as a catalyst at the interphase between the aqueous and organic phases as shown in Figure 1. The reaction medium of phase-boundary catalysis system for the catalytic reaction of immiscible aqueous and organic phases consist of three phases; an organic liquid phase, containing most of the substrate, an aqueous liquid phase containing most of the substrate in aqueous phase and the solid catalyst. The two liquid phases are almost completely insoluble in one another.