![]() ![]() ![]() The dichromates are used as oxidizing agents in quantitative analysis, to make molds for the firing of bricks, and also used in tanning leather (the waste effluent is toxic so alternatives are being investigated).ĪChromium compounds are widely used as industrial catalysts and pigments (in bright green, red yellow, and orange colours). TheChromium is used to harden steel, to manufacture stainless steel (Contains10.5% Chromium) and to produce several useful alloys.ĪChromium is mostly used in plating to give a steel a polished silvery mirror coating (corrosion resistance), also to produce a hard, beautiful surface, Which is commonly used in Chromium-plated car and lorry parts, such as bumpers.Īll compounds of chromium are colored, and The most important chromates are those of sodium and potassium dichromate (Na 2Cr 2O 7 & K 2Cr 2O 7), and the potassium and ammonium chrome alums (Chromium (III) potassium sulfate, KCr(SO 4) 2). Reaction of, moderately oxidizing at high pH:ĬrO 4 2- + 4 H 2O + 3 e – → Cr(OH) 3 + 5 OH – – Chromium Historyĭiscovery and first isolation: Louis Nicolas Vauquelin (1794, 1797) In Paris (France) Chromium Uses Reaction of Chromate anion (CrO 4 2-) and Dichromate (Cr 2O 7 2-) anions exist in equilibrium:Ģ 2- + 2H + ⇌ 2- + H 2OĪ Reaction shows Both the chromate and dichromate anions are strong oxidizing reagents at low pH:Ĭr 2O 7 2- + 14 H 3O + + 6 e – → 2 Cr 3+ + 21 H 2O Similar results are seen for sulphuric acid (H 2SO 4) but pure samples of chromium may be resistant to attack.Ĭhromium metal does not react with nitric acid (HNO 3) and in fact is passivated (make unreactive by altering the surface layer or coating the surface with a thin inert layer). Metallic chromium dissolves in dilute hydrochloric acid (HCL), and forming Cr(II) and hydrogen gas (H 2), and in this aqueous solution, Cr (II) is present as the complex ion 2+.Ĭr (s) + 2 HCL (aq) → Cr 2+ (aq) +2 Cl – (aq) + H 2 (g) Under still milder conditions, The metal reacts with the halogens, and forms Chromium trihalides:Ģ Cr (s) + 3 F 2 (g) → 2 CrF 3 (s) (chromium (III) fluoride)Ģ Cr (s) + 3 Cl 2 (g) → 2 CrCl 3 (s) (chromium (III) chloride)Ģ Cr (s) + 3 Br 2 (g) → 2 CrBr 3 (s) (chromium (III) Bromide)Ģ Cr (s) + 3 I 2 (g) → 2 CrI 3 (s) (chromium (III) Iodide) Isotopes: 50 Cr 51 Cr 52 Cr 53 Cr 54 Cr IsotopeĪChromium doesn’t react with air and water, at normal temperature.Ĭhromium reacts directly with fluorine (F 2), at 400☌ and 200-300 atmospheric pressure, it forms:Ĭr (s) + 3 F 2 (g) → CrF 6 (s) (chromium (VI) fluoride)Ģ Cr (s) + 5 F 2 (g) → 2 CrF 5 (s) (chromium(V) fluoride) Ionization energies: 1st: 653.89 kJ.mol 2nd: 1590.59 kJ/mol 3rd: 2987 kJ/molīody Centered Cubic (BCC) Reactivity of ChromiumĮlectron affinity: 64.3 kJ/mol Nuclear Properties of Chromium Sound Speed: 5940 m/s Atomic Properties of Chromium Molar magnetic susceptibility: 2.314×10 -9 m 3/mol Physical Properties of Chromiumĭensity: 7.19 g/cm 3 (In solid) 6.3 g/cm 3 (In Liquid at M.P) Mass magnetic susceptibility: 44.5×10 -9 m 3/kg Volume magnetic susceptibility: 0.0003177 Magnetic susceptibility (x mol): +280×10 -6 cm 3/mol Neel Point (magnetic ordering temperature) T N: 393 K (Temperature, above which an antiferromagnetic material becomes paramagnetic) Electrical properties of ChromiumĪ Electrical type: Conductor Magnetic Properties of Chromium Chromium Electron Configuration Thermal Properties of Chromiumĭebye temperature: 460 K (186.85 oC, 368.33 oF) ![]()
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