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2 He helium-4; Hoffer et al. 0.19085 g/cm 3 (from 20.9730 cm 3 /mole; hcp crystal melting to He-II superfluid at 0 K, 25.00 atm) : 0.19083 g/cm 3 (from 20.9749 cm 3 /mole; at local min. density, hcp melting to He-II: 0.884 K, 25.00 atm)
The Pourbaix diagram for chromium in pure water, perchloric acid, or sodium hydroxide [1] [2] Chromium compounds are compounds containing the element chromium (Cr). Chromium is a member of group 6 of the transition metals. The +3 and +6 states occur most commonly within chromium compounds, followed by +2; charges of +1, +4 and +5 for chromium ...
It is obtained on a vast scale by roasting chromium ores in air in the presence of sodium carbonate: 2Cr 2 O 3 + 4 Na 2 CO 3 + 3 O 2 → 4 Na 2 CrO 4 + 4 CO 2. This process converts the chromium into a water-extractable form, leaving behind iron oxides.
It may also be formed by reacting chromium(III) chloride with H 2 S, reducing chromium(III) sulfide with hydrogen, or by double replacement reaction of lithium sulfide with chromium(II) chloride. [5] Cr + S → CrS Cr + H 2 S → CrS + H 2 2 CrCl 3 + 3 H 2 S → 2 CrS + S + 6 HCl Cr 2 S 3 + H 2 → 2 CrS + H 2 S Li 2 S + CrCl 2 → 2 LiCl + CrS
Change in volume with increasing ethanol fraction. The molar volume of a substance i is defined as its molar mass divided by its density ρ i 0: , = For an ideal mixture containing N components, the molar volume of the mixture is the weighted sum of the molar volumes of its individual components.
For example, sulfuric acid (H 2 SO 4) is a diprotic acid. Since only 0.5 mol of H 2 SO 4 are needed to neutralize 1 mol of OH −, the equivalence factor is: f eq (H 2 SO 4) = 0.5. If the concentration of a sulfuric acid solution is c(H 2 SO 4) = 1 mol/L, then its normality is 2 N. It can also be called a "2 normal" solution.
2 CrCl 3 + Zn → 2 CrCl 2 + ZnCl 2. CrCl 2 can also be prepared by treating a solution of chromium(II) acetate with hydrogen chloride: [6] Cr 2 (OAc) 4 + 4 HCl → 2 CrCl 2 + 4 AcOH. Treatment of chromium powder with concentrated hydrochloric acid gives a blue hydrated chromium(II) chloride, which can be converted to a related acetonitrile ...
Chromium(II) iodide is the inorganic compound with the formula CrI 2. It is a red-brown [1] or black solid. The compound is made by thermal decomposition of chromium(III) iodide. Like many metal diiodides, CrI 2 adopts the "cadmium iodide structure" motif, i.e., it features sheets of octahedral Cr(II) centers interconnected by bridging iodide ...