The copper ion is obtained by the loss of the outermost two electrons of the copper atom. It has a positive valence of 2 and is written as Cu2+, usually blue, copper ion Cu2+stayaqueous solutionIn factHydrated ion[Cu(HtwoO)four]2+Exists in the form of,hydrationCopper ions are blue, so our common copperSalt solutionMost are blue.At room temperature, Cu2+The precipitation starts when pH=5.2, and is complete when pH=6.4.
towardsCupric chlorideWhen water is added to the solution, the concentration of chloride ion in the solution decreases, and the amount of hydrated copper ion increases relatively. The solution mainly presents the color of hydrated copper ion (blue).So we see copper chloridedilute solutionIt is generally blue.
In the same waynitric acidIn the reaction with copper,Dilute nitric acidThe solution obtained by reaction with copper is blue, andConcentrated nitric acidThe solution obtained by reaction with copper is green.This is because concentrated nitric acid and copperReaction time, producing a large number ofNitrogen dioxideThe gas and nitrogen dioxide are yellow when dissolved in the solution. The yellow of nitrogen dioxide is mixed with the blue of hydrated copper ion to form the green we see.
Composition
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Schematic diagram of copper ion structure
And inCupric chlorideIn the solution of2+, andChloride ionCl-Tetrachloro copper complex ion [CuCl4] formed by combining with copper ion2-The color of the ion is yellow.When adding in saturated copper chloride solutionsodium chlorideOr otherschlorideAnd accessHydrogen chlorideThe green of the solution will be further "yellowed", making the solution bright yellow green, while the solution adhered to the white porcelain wall will be yellow, which is related to the physical tension that changes the tetrachloride copper ionequilibrium constantIn the solution, a large amount of water makes the conversion of copper tetrachloride ion reversible, so it cannot be made yellow.According to the principle of optics, blue and yellowMixed colorIt is green, which is why the commonCupric chlorideThe reason why the solution is green.
major function
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Generate copper
Copper ion can pass throughReduction reactionProduce copper, which can generate copper ions through oxidation reaction,Copper saltDissolve in water or melt to get copper ion, which can be mixed withHydroxyl ionGenerate water insolubleCu(OH)2Blue precipitation, which is also one of the methods for testing copper ions.Copper ions exist inAlkaline solutionSediment will be formed in.
