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Combinations of the above techniques produce "hybrid" or "hyphenated" techniques. Several examples are in popular use today and new hybrid techniques are under development. For example, gas chromatography-mass spectrometry, LC-MS, GC-IR, LC-NMR, LC-IR, CE-MS, ICP-MS, and so on.
Hyphenated separation techniques refers to a combination of two or more techniques to separate chemicals from solutions and detect them. Most often the other technique is some form of chromatography. Hyphenated techniques are widely used in chemistry and biochemistry. A slash is sometimes used instead of hyphen, especially if the name of one of the methods contains a hyphen itself.
Examples of hyphenated techniques:
ISWT 13. Law of mass action (LMA).
K.Guldberg and P.Waage (1867) clearly stated the Law of Mass Action (sometimes termed the Law of Chemical Equilibrium) in the form: the rate of any chemical reaction is proportional to the product of the masses of the reacting substances, with each mass raised to a power equal to the coefficient that occurs in the chemical equation. “Active mass” was interpreted as concentration and expressed in moles per liter. By applying the law to homogeneous systems, that is to systems in which al1 the reactants are present in one phase, for example in solution, we can arrive at a mathematical expression for the condition of equilibrium in a reversible reaction.
The laws of mass action have universal importance in chemistry. The law of mass action is a reaction that states that the values of the equilibrium – constant expression Kc are constant for a particular reaction at a given temperature, whatever equilibrium concentrations are substitute.
aA + bB ↔ cC + dD 
Getting the maximum amount of product from a reaction depends on the proper selection of reaction conditions. By changing these conditions, we can increase or decrease the yield of product. We might change the yield by:
1. Changing concentrations by removing products or adding reactants to the reaction vessel.
2. Changing the partial pressure of gaseous reactants and products.
3. Changing the temperature.
The equilibrium-constant expression is defined in terms of the balanced chemical equation. All analytical reactions, as a rule, run in solutions. For solutions we cannot change the pressure. Sometimes we might heat or freeze the reaction vessel. But, in general, all reactions (processes) occur at isothermal condition.
Therefore, we may use the equilibrium-constant expression in term of concentrations for both types of equilibrium:
I. A homogeneous equilibrium is an equilibrium that involves reactants and products in a single phase (in solution, particle):
– solutions of electrolytes;
– protolytic equilibrium (hydrolysis, buffer systems);
– complex compounds;
– redox systems.
II. A heterogeneous equilibrium is an equilibrium involving reactants and products in more than one phase:
a) liquid–solid systems:
– saturated solution–precipitate (sediment);
– colloids;
b) liquid–liquid system:
– extraction.
In analytical chemistry law of mass action use for calculation of:
1) equilibrium ions concentration of dissociated weak electrolyte;
2) equilibrium concentration of reactants and products of chemical-analytical process;
3) equilibrium concentration of hydrogen and hydroxide ions and ionization degree of electrolytes solutions;
4) equilibrium concentration of hydrogen and hydroxide ions in buffers and solutions of hydrolyzed salts;
5) equilibrium concentration of cations and anions and solubility of electrolytes;
6) equilibrium concentration of ions of oxidant and reduce agent in redox reactions;
7) equilibrium concentration of ions in complex compounds solutions;
8) equilibrium-constants of various chemical processes.
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