PREPARATION OF TRANS ISOMER OF DIOXALATO DIAQUO CHROMATE (III)
Theory:
Trans isomers of potassium dioxalate dichromate (III) can be prepared by mixing a solution of oxalic acid with potassium dichromate. By slow evaporation, rose-colored crystals are formed at a concentration of about 1/3 volume. These are separated by filtration, and water and finally washed with ethyl alcohol.
Chemical Equation:
K2Cr2O7 + 7(COOH)2 .2H2 O → 2K{Cr(C2O4)2 (H2 O)2 } 2H2O + 6CO2 + 13H2O
Chemical Required:
- Oxalic acid crystals = 6 g
- Potassium dichromate (sold) = 2.0 g
- Alcohol = 10.0 ml
Procedure :
- Take a 400 ml beaker and place 6 grams of oxalic acid crystals in it. Add a small amount of water and heat to dissolve the oxalic acid crystals in a minimal amount of water.
- Take a boiling tube and put 2 grams of potassium dichromate crystals in it and add a small amount of water to it. Heat the potassium dichromate crystals to dissolve in a minimal amount of water.
- Then slowly add the contents of the boiling tube to the contents of the beaker and cover the beaker with a watch glass once the strong reaction is set. After mixing the two solutions thoroughly, cool the dark-colored contents of the beaker and then transfer them to a china dish.
- Let the ingredients of the china dish sit in the air for 36-48 hours and let it concentrate at room temperature so that its volume can be reduced to one-third of the original volume.
- Then, the crystals will be deposited in a china dish which is collected in a suction filter. The crystals are then washed several times with cold water and finally with ethanol.
- These crystals have rose colour with a violet tinge
- Weigh the crystals and record the yield.
Result:
- Yield
- Theoretical yield
- %age yield
- Colour of crystals = Rose colour with a violet tinge.
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