The Chemical Properties Of Nickel

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Nickel is a transition metal element with element symbol Ni, located in group VIII of the fourth period, with atomic number 28. Nickel is a silver-white metal with good mechanical strength and ductility. It is insoluble in water and has strong corrosion resistance to acids and alkalis, but it is easily soluble in dilute nitric acid and aqua regia. High temperature resistance, melting point 1455 °C, boiling point 2730 °C. The density is 8.902g/cm³. It can be used to make currency, etc. It can be plated on other metals to prevent rust.
 
Chemical nature
 
Nickel is insoluble in water and forms a dense oxide film on the surface in humid air at room temperature, which can prevent the body metal from continuing to oxidize. It dissolves slowly in dilute acid and releases hydrogen to produce green positive divalent nickel ion Ni; it is resistant to strong alkalis. Nickel can burn in pure oxygen and emit a dazzling white light. Similarly, nickel can also be burned in chlorine and fluorine gas. It does not react with oxidant solutions including nitric acid. Nickel is a medium-strength reducing agent. Nickel hydrochloric acid, sulfuric acid, organic acids and alkaline solutions are very slow to etch nickel. Nickel slowly dissolves in dilute nitric acid. Fuming nitric acid can passivate the surface of nickel and have corrosion resistance.
 
Like platinum and palladium, nickel can absorb a large amount of hydrogen during passivation. The smaller the particle size, the greater the absorption. The important salts of nickel are nickel sulfate and nickel chloride. Nickel nitrate is also commonly used in laboratories, with crystal water, the chemical formula is Ni(NO3)2·6H2O, green transparent particles, easy to absorb water vapor in the air. Similar to iron and cobalt, it is relatively stable to water and air at room temperature, and can resist alkaline corrosion. Therefore, a nickel crucible can be used to melt alkali in the laboratory.
 
Nickel sulfate (NiSO4) can form alum Ni(SO4)2o6H2O with alkali metal sulfate (MI is an alkali metal ion). +2 valent nickel ions can form coordination compounds. Under normal pressure, nickel can react with carbon monoxide to form highly toxic nickel tetracarbonyl (Ni(CO)4), which will decompose into metallic nickel and carbon monoxide after heating.

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