Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outcome of a particular chemical change, or vice versa. These reactions involve electrons moving via an electronically-conducting phase between electrodes separated by an ionically conducting and electronically insulating electrolyte.
In chemistry, pH, also referred to as acidity, historically denotes "potential of hydrogen". It is a scale used to specify the acidity or basicity of an aqueous solution. Acidic solutions are measured to have lower pH values than basic or alkaline solutions.
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity".
In chemistry, an acid dissociation constant is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a chemical reaction
Solubility equilibrium is a type of dynamic equilibrium that exists when a chemical compound in the solid state is in chemical equilibrium with a solution of that compound. The solid may dissolve unchanged, with dissociation, or with chemical reaction with another constituent of the solution, such as acid or alkali. Each solubility equilibrium is characterized by a temperature-dependent solubility product which functions like an equilibrium constant. Solubility equilibria are important in pharmaceutical, environmental and many other scenarios.
In electrochemistry, the Nernst equation is a chemical thermodynamical relationship that permits the calculation of the reduction potential of a reaction from the standard electrode potential, absolute temperature, the number of electrons involved in the redox reaction, and activities of the chemical species undergoing reduction and oxidation respectively. It was named after Walther Nernst, a German physical chemist who formulated the equation.
Søren Peter Lauritz Sørensen was a Danish chemist, famous for the introduction of the concept of pH, a scale for measuring acidity and alkalinity.
The quinones are a class of organic compounds that are formally "derived from aromatic compounds [such as benzene or naphthalene] by conversion of an even number of –CH= groups into –C(=O)– groups with any necessary rearrangement of double bonds, resulting in "a fully conjugated cyclic dione structure". The archetypical member of the class is 1,4-benzoquinone or cyclohexadienedione, often called simply "quinone". Other important examples are 1,2-benzoquinone (ortho-quinone), 1,4-naphthoquinone and 9,10-anthraquinone.
In electrochemistry, standard electrode potential, or , is a measure of the reducing power of any element or compound. The IUPAC "Gold Book" defines it as: "the value of the standard emf of a cell in which molecular hydrogen under standard pressure is oxidized to solvated protons at the left-hand electrode".
In electrochemistry, the standard hydrogen electrode, is a redox electrode which forms the basis of the thermodynamic scale of oxidation-reduction potentials. Its absolute electrode potential is estimated to be 4.44 ± 0.02 V at 25 °C, but to form a basis for comparison with all other electrochemical reactions, hydrogen's standard electrode potential is declared to be zero volts at any temperature. Potentials of all other electrodes are compared with that of the standard hydrogen electrode at the same temperature.
The equilibrium constant of a chemical reaction is the value of its reaction quotient at chemical equilibrium, a state approached by a dynamic chemical system after sufficient time has elapsed at which its composition has no measurable tendency towards further change. For a given set of reaction conditions, the equilibrium constant is independent of the initial analytical concentrations of the reactant and product species in the mixture. Thus, given the initial composition of a system, known equilibrium constant values can be used to determine the composition of the system at equilibrium. However, reaction parameters like temperature, solvent, and ionic strength may all influence the value of the equilibrium constant.
Coulometry determines the amount of matter transformed during an electrolysis reaction by measuring the amount of electricity consumed or produced. It can be used for precision measurements of charge, and the amperes even used to have a coulometric definition. However, today coulometry is mainly used for analytical applications. Coulometry is a group of techniques in analytical chemistry. It is named after Charles-Augustin de Coulomb.
A glass electrode is a type of ion-selective electrode made of a doped glass membrane that is sensitive to a specific ion. The most common application of ion-selective glass electrodes is for the measurement of pH. The pH electrode is an example of a glass electrode that is sensitive to hydrogen ions. Glass electrodes play an important part in the instrumentation for chemical analysis and physicochemical studies. The voltage of the glass electrode, relative to some reference value, is sensitive to changes in the activity of a certain type of ions.
The palladium-hydrogen electrode (abbreviation: Pd/H2) is one of the common reference electrodes used in electrochemical study. Most of its characteristics are similar to the standard hydrogen electrode (with platinum). But palladium has one significant feature—the capability to absorb (dissolve into itself) molecular hydrogen.
A silver chloride electrode is a type of reference electrode, commonly used in electrochemical measurements. For environmental reasons it has widely replaced the saturated calomel electrode. For example, it is usually the internal reference electrode in pH meters and it is often used as reference in reduction potential measurements. As an example of the latter, the silver chloride electrode is the most commonly used reference electrode for testing cathodic protection corrosion control systems in sea water environments.
Redox potential is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respectively. Redox potential is expressed in volts (V). Each species has its own intrinsic redox potential; for example, the more positive the reduction potential, the greater the species' affinity for electrons and tendency to be reduced.
1,4-Benzoquinone, commonly known as para-quinone, is a chemical compound with the formula C6H4O2. In a pure state, it forms bright-yellow crystals with a characteristic irritating odor, resembling that of chlorine, bleach, and hot plastic or formaldehyde. This six-membered ring compound is the oxidized derivative of 1,4-hydroquinone. The molecule is multifunctional: it exhibits properties of a ketone, being able to form oximes; an oxidant, forming the dihydroxy derivative; and an alkene, undergoing addition reactions, especially those typical for α,β-unsaturated ketones. 1,4-Benzoquinone is sensitive toward both strong mineral acids and alkali, which cause condensation and decomposition of the compound.
Chloroplatinic acid (also known as hexachloroplatinic acid) is an inorganic compound with the formula [H3O]2[PtCl6](H2O)x (0 ≤ x ≤ 6). A red solid, it is an important commercial source of platinum, usually as an aqueous solution. Although often written in shorthand as H2PtCl6, it is the hydronium (H3O+) salt of the hexachloroplatinate anion (PtCl2−
6). Hexachloroplatinic acid is highly hygroscopic.
A reversible hydrogen electrode (RHE) is a reference electrode, more specifically a subtype of the standard hydrogen electrodes, for electrochemical processes. Unlike the standard hydrogen electrode, its measured potential does change with the pH, so it can be directly used in the electrolyte.
Equilibrium chemistry is concerned with systems in chemical equilibrium. The unifying principle is that the free energy of a system at equilibrium is the minimum possible, so that the slope of the free energy with respect to the reaction coordinate is zero. This principle, applied to mixtures at equilibrium provides a definition of an equilibrium constant. Applications include acid–base, host–guest, metal–complex, solubility, partition, chromatography and redox equilibria.
