This document describes the properties and preparation of chromium(II) acetate hydrate. Chromium(II) acetate hydrate has the molecular formula C8H16Cr2O10 and appears as a brick-red solid. The document outlines the procedure to prepare chromium(II) acetate hydrate by reducing chromium(III) chloride with zinc in the presence of acetic acid and sodium acetate to form a red precipitate of the hydrate. Characterization details are provided, noting it will oxidize in air and is diamagnetic in its pure form.

1. Created By :
Medina Indriati (J2C 007 030)
Melly Wahyuningsih (J2C 007 031)
Milka Ironia Realita (J2C 007 032)

2. 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

3. 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

4. Structure of Cr2(CH3CO2)4(H2O)2

5. 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

6. 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.

7.  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.

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

9. 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

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

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

12. THANK YOU…