![]() Argo introduced the solvated electron concept. Kraus measured the electrical conductance of metal ammonia solutions and in 1907 attributed it to the electrons liberated from the metal. Seely in 1871 used liquid ammonia, whereas Hamilton Cady in 1897 related the ionizing properties of ammonia to that of water. Hogarth repeated the experiments with sodium in 1879–1880. In 1807–1809, he examined the addition of grains of potassium to gaseous ammonia (liquefaction of ammonia was invented in 1823). The observation of the color of metal-electride solutions is generally attributed to Humphry Davy. the use of sodium in ethanol as in the Bouveault–Blanc reduction. Other reactions where sodium is used as a reducing agent also are assumed to involve solvated electrons, e.g. Solvated electrons are involved in electrode processes, a broad area with many technical applications ( electrosynthesis, electroplating, electrowinning).Ī specialized use of sodium-ammonia solutions is the Birch reduction. With nitrous oxide, solvated electrons react to form hydroxyl radicals (HO. The solvated electron reacts with oxygen to form a superoxide radical (O 2. These ligands strongly bind the cations and prevent their re-reduction by the electron. Reactivity Īlthough quite stable, the blue ammonia solutions containing solvated electrons degrade rapidly in the presence of catalysts to give colorless solutions of sodium amide:Ģ +e − → H 2 + 2 NaNH 2 + 10 NH 3Įlectride salts can be isolated by the addition of macrocyclic ligands such as crown ether and cryptands to solutions containing solvated electrons. This value of equivalent conductivity corresponds to a diffusivity of 4,75*10 −5 cm 2s −1. Equivalent conductivity 177 Mho cm 2 is similar to that of hydroxide ion. Its standard electrode potential value is -2.77 V. This implies their possible existence in the upper atmosphere of Earth and involvement in nucleation and aerosol formation. Solvated electrons can be found even in the gas phase. Below pH = 9.6 the hydrated electron reacts with the hydronium ion giving atomic hydrogen, which in turn can react with the hydrated electron giving hydroxide ion and usual molecular hydrogen H 2. Solvated electrons are involved in the reaction of alkali metals with water, even though the solvated electron has only a fleeting existence. Solvated electron solutions of the alkaline earth metals magnesium, calcium, strontium and barium in ethylenediamine have been used to intercalate graphite with these metals. THF dissolves alkali metal, but a Birch reduction (see § Applications) analogue does not proceed without a diamine ligand. ![]() In the same concentration range the overall density decreases by 30%.Īlkali metals also dissolve in some small primary amines, such as methylamine and ethylamine and hexamethylphosphoramide, forming blue solutions. Above 8 MPM the solution is bronze/gold-colored. ![]() At 4 MPM a liquid-liquid phase separation takes place: the less dense gold-colored phase becomes immiscible from a denser blue phase. At around 8 MPM, a "transition to the metallic state" (TMS) takes place (also called a "metal-to-nonmetal transition" (MNMT)). When the concentration is increased in this range electrical conductivity increases from 10 −2 to 10 4 ohm −1 cm −1 (larger than liquid mercury). The colors are characteristic of solvated electrons at electronically insulating and metallic concentrations, respectively.Ī lithium–ammonia solution at −60 ☌ is saturated at about 15 mol% metal (MPM). The solution at the top has a dark blue color and the lower one a golden color. Solutions obtained by dissolution of lithium in liquid ammonia. The reaction is reversible: evaporation of the ammonia solution produces a film of metallic sodium. Solvated electrons in ammonia are the anions of salts called electrides. The diffusivity of the solvated electron in liquid ammonia can be determined using potential-step chronoamperometry. ![]() The blue colour of the solution is due to ammoniated electrons, which absorb energy in the visible region of light. For alkali metals in liquid ammonia, the solution is blue when dilute and copper-colored when more concentrated (> 3 molar). Liquid ammonia will dissolve all of the alkali metals and other electropositive metals such as Ca, Sr, Ba, Eu, and Yb (also Mg using an electrolytic process ), giving characteristic blue solutions. ![]()
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