Inorganic Chemistry Practical by Dr Deepak Pant (the reading strategies book txt) 📖

1970), p. 256. [QC457.N3]


3. Preparation of Ni (DMG)2 Complex
The precipitation reaction of the nickel with the DMG is:


Ni (DMG)2 can be obtained by 1:2 stoichiometry reaction between any nickel salt and DMG.


4. Preparation of Prussian blue - Fe4[Fe(CN)6]3•14H2O
Materials:
Item Amount per student
Iron (III) Chloride (FeCl3) 4 g
Potassium Ferrocyanide (K4[Fe(CN)6]) 1.5 g
Filter paper 1
Equipment:
Item Amount per student Amount for 24 students
Buchner funnel 1
Filter flask 1
Tubing 1
Filter-vac rubber rings (for suction flasks) 1
Fe3+ + 3 [Fe(CN)6]4- → Fe4[Fe(CN)6]3
Procedure: Dissolve iron(III) salt in water in a beaker and K4[Fe(CN)6] in another one.
Slowly add K4[Fe(CN)6] solution to the iron(III) solution, while stirring. Let the blue precipitate settle. Decant the supernatant liquid and wash the precipitate with water. Swirl the mixture and let the precipitate settle, decant and repeat the washing once more. Filter out the product and let it dry by air pulling air through the filter for a few minutes.
1. Prepare a saturated solution of iron (III) chloride by placing 3.7 g FeCl3 in a small beaker with 5 mL distilled water. Use a graduated cylinder to measure the volume of water you used. Stir to dissolve.
2. Separately, prepare a saturated solution of potassium ferrocyanide by placing 1.39 g K4[Fe(CN)6] in another beaker with 5 mL distilled water
3. Make the Prussian Blue by pouring the potassium ferrocyanide solution into the beaker with the ferric chloride solution. Stir with a glass rod.
4. Obtain filter paper that fits the Buchner funnel (so it lays flat in the bottom). Set up the aspirator by connecting a piece of tubing from the little side-arm on the filter flask to the similar arm sticking out from the side of the faucet.
5. Turn on the faucet to create suction. Then pour your reaction mixture into the funnel.
Scrape the entire blue product into the funnel: use a little distilled water to rinse the beaker.
6. Dry to obtain Prussian blue.


5. Preparation of Mn(acac)3
Acetylacetonate (acac) is a common monoanionic bidentate ligand derived from the monodeprotonation of acetylacetone (2,4-pentanedione). The binding of this ligand to a transition metal ion can be thought of as consisting of a covalent bond through one oxygen and a dative bond through the other oxygen. In actuality, the bonding is usually delocalized and is most correctly drawn using the delocalized resonance structure shown on the right.

Mn(acac)3 will synthesize according to the following equation:


5. Synthesis of Turnbull s Blue (iron (II) hexacyanoferrate(III)] )complex.
Prussian blue and Turnbull’s blue are similar kind of dyes, their difference can explained by the different method of preparation as:
Fe2+ + Fe(CN)63- == Turnbull s Blue
Fe3+ + Fe(CN)64- == Prussian Blue
Turnbull s Blue can be prepared by the 1:1 stoichiometry reaction of FeSO4.7H2O and K4Fe(CN)6

6. Preparation of copper ammine sulphate [Cu(NH3)4]SO4.H2O

CuSO4 + 4 NH3(aq) + H2O → [Cu(NH3)4]SO4.H2O

Material: CuSO4.5H2O, NH3(aq), C2H5OH
Procedure: Place 5 g of finely powdered copper sulphate, CuSO4.5H2O, in a small beaker, pour upon it 7.5 ml of concentrated ammonia and 3 ml of water. Shake it for about 1 minute and then heat it gently until all the solid dissolves. Add about 10 ml of ethanol to the solution, let it stand for about one hour and filter off the crystals. Wash them with a mixture of 5 ml of concentrated ammonia and 5 ml of ethanol. Dry them on air in the hood.
[Cu(NH3)4]SO4.H2O – dark blue crystals, soluble in water (18 g in 100 ml of water at
21.5 oC), stable on air.

7. Preparation of μ-hydroxo-bis(pentaamminechromIII) – work in a fume
Hood

2 CrCl2 + 9 NH3 + NH4Cl + ½ O2 → [(NH3)5Cr-OH-Cr(NH3)5]Cl5
Material: K2Cr2O7, HCl, C2H5OH, NH4Cl, NH3(aq)

Procedure: Spread 12 g of K2Cr2O7 and mix it with 7.2 ml of C2H5OH and 28.2 ml of concentrated HCl in a flask. Write equation of this reaction.
Put the calculated amount of Zn (for reduction of Cr3+ to Cr2+ and 50 % excess) into a 250-ml flask and add CrCl3 solution. Close the flask with a stopper with two holes. One is for a separatory funnel with 15 ml of concentrated HCl, the second is for a glass tube. Observe change of colour from green (Cr3+) to blue (Cr2+) after adding HCl. Pour the solution to the flask with a mixture of 250 ml NH3(aq) and 100 g of NH4Cl. Swirl the flask and observe change of colour to red. Red crystals should precipitate in a few minutes. Filter off the crystals and wash them with diluted HCl (1:2). Recrystallize the crude product by dissolving in small volume of water and precipitate with diluted HCl (1:2). Filter off the pure product, wash it with a small amount of ethanol and dry it on air.

[(NH3)5Cr-OH-Cr(NH3)5]Cl5 – red crystals, soluble in water. Creates blue complex
[(NH3)5Cr-O-Cr(NH3)5]Cl4 in NH3 or NaOH solutions


8. Preparation of potassium tris(oxalate)ferrate(III) trihydrate
Fe(OH)3 + 3 KHC2O4 → K3[Fe(C2O4)3] + 3 H2O
Material: FeSO4.7H2O or (NH4)2Fe(SO4)2.4H2O, K2C2O4, H2C2O4, HNO3, ethanol Procedure: Dissolve 35 g of FeSO4.7H2O in 100 ml of warm water and add slowly diluted HNO3 (1:1) to oxidize Fe2+. Add NH3(aq) to the solution until the precipitation of Fe(OH)3 is completed. Let the precipitate settle and decant the liquid. Filter out the precipitate and wash it with hot water. Prepare a hot solution of 44 g of KHC2O4 (calculate it as a mixture of K2C2O4 and H2C2O4) in 100 ml H2O. Add precipitate of Fe(OH)3 in small portions to this solution. Filter the resulting solution and evaporate it on a steam bath to crystallization. Filter out and wash the crystals on the Buchner funnel with ethanol/water 1:1 and finally with acetone. Transfer the product to a dry filter paper and let it dry in air.
K3[Fe(C2O4)3].3H2O – green crystals, photosensitive and decomposes due to influence of light:
2 K3[Fe(C2O4)3] → K2[Fe(C2O4)2] + K2C2O4 + 2 CO2
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Publication Date: 06-13-2010

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