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The chloralkali process (also chlor-alkali and chlor alkali) is an industrial process for the electrolysis of sodium chloride (NaCl) solutions. It is the technology used to produce chlorine and sodium hydroxide (caustic soda), [ 1 ] which are commodity chemicals required by industry.
Sodium chloride (NaCl) melts at 801 °C (1074 Kelvin), but a salt mixture can be kept liquid at a temperature as low as 600 °C at the mixture containing, by weight: 33.2% NaCl and 66.8% CaCl 2. If pure sodium chloride is used, a metallic sodium emulsion is formed in the molten NaCl which is impossible to separate.
The Castner–Kellner process is a method of electrolysis on an aqueous alkali chloride solution (usually sodium chloride solution) to produce the corresponding alkali hydroxide, [1] invented by American Hamilton Castner and Austrian Carl Kellner in the 1890s.
Considering the industrial production of hydrogen, and using current best processes for water electrolysis (PEM or alkaline electrolysis) which have an effective electrical efficiency of 70–80%, [68] [73] [74] producing 1 kg of hydrogen (which has a specific energy of 143 MJ/kg) requires 50–55 kW⋅h (180–200 MJ) of electricity.
A low voltage DC current is applied, electrolysis happens producing sodium hypochlorite and hydrogen gas (H 2). The solution travels to a tank that separates the hydrogen gas based on its low density. [1] Only water and sodium chloride are used. The simplified chemical reaction is: NaCl + H 2 O + energy → NaOCl + H 2 [citation needed]
Important examples of electrolysis are the decomposition of water into hydrogen and oxygen, and bauxite into aluminum and other chemicals. Electroplating (e.g., of copper, silver, nickel, or chromium) is done using an electrolytic cell. Electrolysis is a technique that uses a direct electric current (DC).
Note: ρ is density, n is refractive index at 589 nm, [clarification needed] and η is viscosity, all at 20 °C; T eq is the equilibrium temperature between two phases: ice/liquid solution for T eq < 0–0.1 °C and NaCl/liquid solution for T eq above 0.1 °C.
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula . For example, a solution of table salt , also known as sodium chloride (NaCl), in water would be represented as Na + (aq) + Cl − (aq) .