Created By :Medina Indriati (J2C 007 030)

Melly Wahyuningsih (J2C 007 031)Milka Ironia Realita (J2C 007 032)

What is Chromium(II)acetate

Hydrate???

Chromium(II) acetate, better known as chromous acetate, is the coordination compound with the formula Cr2(CH3CO2)4(H2O)2 or Cr2(OAc)4(H2O)2

Properties Molecular formula C8H16Cr2O10

Molar mass 376.2 g/mol Appearance brick-red solid Density 1.79 g/cm3 Melting point dehydrates >100C Solubility in water soluble in hot

water, MeOH

Structure of Cr2(CH3CO2)4(H2O)2

Preparation of Cr2(CH3CO2)4(H2O)2

Reagent required :- 15 g CrCl3.6H2O- 12 g of mossy zink- 90 g of NaOAc.3H2O- 25 ml of concentrated HCl- 200 ml of ice-cold boiled water- 75 ml of alcohol (95%)- 75 ml of ether

Procedure Place the mossy zink and solution of the

CrCl3.6H2O in 50 ml of water in the flask. Slowly add concentrated HCl until the

solution has a blue color. Make a slurry of the NaOAc.3H2O in 80 ml

of water. While hydrogen gas is still being evolved,

pinch the rubber tubing to force the chromium(II) chloride solution over into the sodium acetate solution that is in the Erlenmeyer flask.

Dip the delivery tube under the sodium acetate solution during the transfer, a red precipitate of chromous acetate forms.(note : do not at the chromium solution to the acetate unless the solution is a pure blue)

Filter the chromous acetate on a sintered-glass funnel and wash it with cold air-free water.

Do not stir up the precipitate with the wash water very much or the filtration may proceed slowly.

Wash with the alcohol and then the ether, and finally suck the crysstals as dry as possible on the funnel.

Characterization

If air is admitted to the sample, it will gradually turn to the gray-green color characteristic of the oxidized material.

Pure[Cr(OAc)2]2.2H2O is diamagnetic

Analysis

[Cr(OAc)2]2·2H20 can be analyzed by Spectroscopy Infared (IR)

Reaction 2 Cr3+ + Zn → 2 Cr2+ + Zn2+ 2 Cr2+ + 4 OAc- + 2 H2O → Cr2(OAc)4(H2O)2 4 HO2CR + 2 Cr(C5H5)2 → Cr2(O2CR)4 + 4 C5H6

The overall net reaction is the sum of the abovereaction :

2CrCl3·6H2O + Zn + 4 NaOAc·3H2O →[Cr(OAc)2]2·2H20 + ZnCl2 + 4 NaCl + 22 H20

THANK YOU…