I am interested in preparing a bimetallic system to run an adsorption study. I want to combine an anion [Cr(VI)- salt used: Potassium dichromate] and a cation [Ni(II)- Ni(NO3)2.6H2O or Cd(II)- CdCl2]. Initially, I combined Lead nitrate and Potassium dichromate, to have a bimetallic system containing Pb and Cr. As my study required a set pH, lead chromate is formed at this pH (2 and 5).
My concern is as follows:
1) Will the state be similar if I combine Ni and Cr salts? OR Cd and Cr salts?
2) Would it result in precipitate formation?
2) Which among the above will be a better combination?
All suggestions will be appreciated. Thank you
i tried a geo-chemical software for you, there is no Cadmium chromate or Nickel chromate formed. the reason is either that Cadmium chromate and Nickel chromate do not exist or that they are more soluble than cadmium hydroxide or Nickel hydroxide.
but lead chromate does form as precipitate! I used 2 mmole for each reactant in the modelling
please let me know you want me to run the models under other conditions
Dear Smruthi Prabhu
Nickel compounds moslty are in complex forms and if you want to precipitate its product you should synthesiz it and then purifed it and eventually precipitated it.
Yours
Nickel (II) Chromate (NiCrO4) is an acid-soluble compound, red-brown in color, with high tolerances for heat. It and the ions that compose it have been linked to tumor formation and gene mutation, particularly to wildlife.[2]
Contents
[hide]
1Synthesis
2Properties
3Reaction
4Related
5References
Synthesis[edit]
Nickel (II) Chromate can be formed in the lab by heating a mixture of chromium(III) oxide and nickel oxide at between 700 °C and 800°C under 1000 atmosphere's pressure of oxygen. It can be produced at 535°C and 7.3 bar oxygen,, but the reaction takes days to complete.[3] If the pressure is too low or temperature too high but above 660° then the nickel chromium spinel NiCr2O4 forms instead.[3]
Karin Brandt also claimed to make nickel chromate using a hydrothermal technique.[4][5]
Precipitates of Ni2+ ions with chromate produce a brown substance that contains water.[6]
Properties[edit]
The structure of nickel chromate is the same as for chromium vanadate, CrVO4. Crystals have an orthorhombic structure with unit cell sizes a=5.482 Å, b=8.237 Å, c=6.147 Å. The cell volume is 277.6 Å3 with four formula per unit cell.[5][7]
Nickel chromate is dark in colour, unlike most other chromates which are yellow.[3]
The infrared spectrum of nickel chromate show two sets of absorption bands. The first includes lines at 925, 825, and 800 cm−1 due to Cr-O stretching, and the second has lines at 430, 395, 365 (very weak) due to Cr-O rock and bend and 310 cm−1 produced from Ni-O stretching.[8]
Reaction[edit]
When heated at lower oxygen pressure around 600°C, nickel chromate decomposes to the nickel chromite spinel, nickel oxide and oxygen.[3]
4NiCrO4 → 2NiCr2O4 + 2NiO + 3O2 (gas)
Related[edit]
Nickel chromates can also crystallize with ligands [Ni(1,10-phenanthroline)CrO4•3H2O]•H2O which forms triclinic olive coloured crystals, and orange crystals of Ni(1,10-phenanthroline)3Cr2O7•3H2O and yellow powdered Ni(1,10-phenanthroline)3Cr2O7•8H2O.[6]
References[edit]
Jump up^ Perry, Dale L. Handbook of Inorganic Compounds, Second Edition. CRC Press. p. 290. ISBN 9781439814628.
Jump up^ Eisler, R. (1998). Nickel Hazards to Fish, Wildlife, and Invertebrates: a Synoptic Review. Laurel: U.S. Geological Survey
^ Jump up to:a b c d Muller, Olaf; Roy, Rustum; White, William B. (December 1968). "Phase Equilibria in the Systems NiO-Cr2,O3,-O2, MgO-Cr2O3-O2, and CdO-Cr2,O3,-O2, at High Oxygen Pressures". Journal of the American Ceramic Society. 51 (12): 693–699. doi:10.1111/j.1151-2916.1968.tb15930.x.
Jump up^ Brandt, Karin (1943). "X-Ray Analysis of CrVO4 and isomorphous compounds". Arkiv for Kemi, Mineralogi och Geologi. 17A (6): 1–13. (not consulted)
^ Jump up to:a b Muller, Olaf; White, William B.; Roy, Rustum (September 1969). "X-ray diffraction study of the chromates of nickel, magnesium and cadmium". Zeitschrift für Kristallographie. 130 (1-6): 112–120. doi:10.1524/zkri.1969.130.1-6.112.
^ Jump up to:a b Bronowska, W; Staszak, Z; Daszkiewicz, M; Cieślak-Golonka, M; Wojciechowska, A (May 2002). "Systematic investigation of the [Ni2+–phen–CrO42−] system; dichromate species isolated from alkaline solutions". Polyhedron. 21 (9-10): 997–1003. doi:10.1016/S0277-5387(02)00912-9.
Jump up^ Baran, E. J (May 1998). "Materials belonging to the CrVO4 structure type: preparation, crystal chemistry and physicochemical properties". Journal of Materials Science. 33 (10): 2479–2497. doi:10.1023/A:1004380530309.
Jump up^ Muller, Olaf; White, William B.; Roy, Rustum (August 1969). "Infrared spectra of the chromates of magnesium, nickel and cadmium". Spectrochimica Acta Part A: Molecular Spectroscopy. 25 (8): 1491–1499. doi:10.1016/0584-8539(69)80133-9.
Thank you so much, everyone, for your valuable answers. As mentioned by Ruiqiang Liu and Parisa Ziarati I did not obtain any precipitate. Thank you, Ruiqiang Liu, for carrying out modelling for confirmed answer and further help offered.
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