Germanium (old translation) is a chemical element whose chemical symbol is Ge, atomic number is 32, atomic weight 72.64. In the periodic table of the chemical elements are located in the 4th cycle and the IVA family. Germanium elemental is a kind of gray classes, metal luster, qualitative hard, belong to the carbon group, chemical properties and kin tin similar to silicon, insoluble in water, hydrochloric acid, dilute caustic solution, soluble in aqua regia, concentrated nitric acid or sulfuric acid, with both sexes, therefore, soluble in the molten alkali, alkaline peroxide, alkali metal nitrate or carbonate, relatively stable in the air, in nature, a total of five germanium isotope: 70,72,73,74,76, above 700 ℃ and oxygen generated GeO2 and above 1000 ℃, with hydrogen powder germanium can burn in the presence of chlorine or bromine, germanium is excellent semiconductor, as a high frequency current detection and rectifier with alternating current (ac), in addition, can be used in the infrared materials, precision instruments, the catalyst. Germanium compounds can be used to make fluorescent panels and various refractive index glass.
Germanium, tin and lead are the same group in the periodic table of the elements, which were discovered and utilized by the ancient people, and the germanium has not been mined by the industry since long ago. This is not because germanium is less abundant in the earth's crust, but because it is one of the most dispersed elements in the earth's crust
Germanium stable chemical properties, temperature not with air or water, but during 600 ~ 700 ℃, germanium dioxide generated quickly. It doesn't work with hydrochloric acid and dilute sulfuric acid. When concentrated sulfuric acid is heated, germanium will dissolve slowly. In nitric acid, wang water, germanium is easy to dissolve. The alkaline solution and germanium are weak, but the molten base is in the air and can dissolve germanium rapidly. Germanium does not work with carbon, so it melts in the graphite crucible and is not contaminated by carbon.
Germanium in the position of the periodic table between metal and nonmetal, therefore has many similar to the nature of the nonmetal, it known as the "inferior metal" in chemical, outer electron configuration for the 4 s 4 p squared squared. But its chemical properties are similar to those of neighboring families, especially arsenic and antimony. There are very few germanium compounds in chemistry or toxicology. The dioxides of germanium, a white powder that is slightly soluble in water, form Germanic acid, which is similar to silicic acid. Germanium tetrachloride is an unstable liquid, and germanium tetrafluoride is a gas that is easily hydrolyzed in water. Germanium hydride (germanium) is a relatively stable gas. Organic germanium compounds, alkyl can replace a number of Ge atoms, as well as tin, mercury, arsenic and other similar, but less toxic. The germanium element and its two oxides are not strong, and the germanium tetrahalide is excitant, and germanium hydrogenation is the most toxic. Germanium is not soluble in dilute acid and alkali, but is soluble in concentrated sulfuric acid.
Germanium is stable at room temperature, but it also generates the GeO monolayer, which gradually becomes the GeO2 monolayer. When the surface of germanium adsorbs water vapor, it destroys the passivation properties of the oxide film and generates thick oxides.
Germanium is oxidized at a higher temperature and is accompanied by a phenomenon of weightlessness, because GeO is generated because of its strong volatility. Researchers studied germanium surface oxidation process, first at 600 ℃ with CO reduction germanium, to eliminate the germanium surface oxygen or oxygen adsorption. Again in 25 ~ 400 ℃, 10 kpa germanium oxide under oxygen pressure, only 1 min or layer to form the first oxidation. When the temperature exceeds 250 ℃ quickly form the oxide layer. When the temperature increases, the oxidation rate slows down significantly. 3 h at 400 ℃ oxidation, GeO2 membrane formation thickness of 1.75 nm.
Germanium is different in different solvents. The solution-potential of n-type germanium is slightly positive than p, so the former is faster in the same solution. Germanium is soluble in hot acid, thermo-base and H2O2 of oxidant. Difficult to dissolve in dilute sulfuric acid, hydrochloric acid and cold lye. Germanium in 100 ℃ is insoluble in water, and saturation of oxygen in water at room temperature, dissolving speed is close to 1 ug/cm. (h).
H2O2 dissolution of germanium
3% of H2O2 at room temperature can slowly dissolve lump of germanium, heating to 90 ~ 100 ℃ dissolve faster. N germanium in 100 ℃ of H2O2 dissolution rate is influenced by the concentration of H2O2.
(1) germanium is oxidized to GeO, which forms a single layer on the surface
(2) further oxidation is GeO2 GeO+H2O2=GeO2+H2O
(3) the GeO2 + H2O = H2GeO3
When there is a base in solution, germanium acid and alkali are used to produce sodium germaniate and accelerate the dissolution of germanium. H2GeO3 + NaOH = Na2GeO3 + 2 h2o
Germanium dissolves in sulfuric acid
90 ℃ when sulfuric acid reaction with block with trace germanium, week-long germanium loss of 1%
The dissolution of germanium in nitric acid
Concentrated nitric acid can corrode the surface of massive germanium. The dissolution rate of germanium in nitric acid is influenced by the concentration of nitric acid, stirring speed and temperature.
Germanium and lye
Sodium hydroxide and potassium hydroxide aqueous solution and the effect of germanium is slow, but molten sodium hydroxide, potassium hydroxide, Na2CO3, Na2O2, NaB4O7 quickly dissolve various forms of germanium, generate germanate alkali metal. 5. The dissolution of germanium in certain salt solutions
Germanium can be soluble in some electrolyte solutions such as sodium sulfate, potassium chloride, nitrate, cesium chloride and lanthanum chloride.
When heated with other substances, the powdery germanium can be burned in chlorine and bromine, producing four halogenated germanium, and the dry HCl gas can corrode germanium.