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In colloidal and surface chemistry, the critical micelle concentration ( CMC) is defined as the concentration of surfactants above which micelles form and all additional surfactants added to the system will form micelles. [ 1] The CMC is an important characteristic of a surfactant. Before reaching the CMC, the surface tension changes strongly ...
Hammett equation. In organic chemistry, the Hammett equation describes a linear free-energy relationship relating reaction rates and equilibrium constants for many reactions involving benzoic acid derivatives with meta- and para- substituents to each other with just two parameters: a substituent constant and a reaction constant. [ 1][ 2] This ...
v. t. e. The neutron–proton ratio ( N/Z ratio or nuclear ratio) of an atomic nucleus is the ratio of its number of neutrons to its number of protons. Among stable nuclei and naturally occurring nuclei, this ratio generally increases with increasing atomic number. [ 1] This is because electrical repulsive forces between protons scale with ...
The uranium-238 series is a series of α (N and Z less 2) and β− decays (N less 1, Z plus 1) to nuclides that are successively deeper into the valley of stability. The series terminates at lead-206, a stable nuclide at the bottom of the valley of stability. Radioactive decay often proceeds via a sequence of steps known as a decay chain.
In thermodynamics, a critical point (or critical state) is the end point of a phase equilibrium curve. One example is the liquid–vapor critical point, the end point of the pressure–temperature curve that designates conditions under which a liquid and its vapor can coexist. At higher temperatures, the gas comes into a supercritical phase ...
Job plot. Within chemistry, a Job plot, otherwise known as the method of continuous variation or Job's method, is a method used in analytical chemistry to determine the stoichiometry of a binding event. The method is named after Paul Job and is also used in instrumental analysis and advanced chemical equilibrium texts and research articles.
The Clausius–Clapeyron relation describes a Phase transition in a closed system composed of two contiguous phases, condensed matter and ideal gas, of a single substance, in mutual thermodynamic equilibrium, at constant temperature and pressure. Therefore, [ 7]: 508. Using the appropriate Maxwell relation gives [ 7]: 508 where is the pressure.
Rubidium–strontium dating. The rubidium-strontium dating method (Rb-Sr) is a radiometric dating technique, used by scientists to determine the age of rocks and minerals from their content of specific isotopes of rubidium ( 87 Rb) and strontium ( 87 Sr, 86 Sr). One of the two naturally occurring isotopes of rubidium, 87 Rb, decays to 87 Sr ...