Preparation of Chromium VI Oxysulphate

Preparation of Chromium(VI) Oxysulphate. (Perform the experiment in a fume cupboard ) a. Preparation of Chromyl Chloride. Assemble an apparatus as shown in Fig. 127a. Dry 12.5 g of sodium chloride and 20 g of potassium dichromate in a drying cabinet at 100-120 °C. Rapidly mix them in a mortar and put the mixture into flask 1. Add 22 ml of a 98% sulphuric acid solution to the reaction 

Pour 15 ml of sulphuryl chloride into flask 2 and weigh it together with its stopper. Pour 50 ml of oleum into flask 1. Heat the latter in a sand bath and carefully distil off sulphur trioxide. Control the amount of distilled trioxide by weighing. When 12 g of sulphur trioxide are collected in flask 2, cool the apparatus and disassemble it. 

Do not wash the apparatus with water Carefully pour out the excess oleum into a jar with a 70% sulphuric acid solution. Rinse the parts of the apparatus with a sulphuric acid solution, gradually lowering its concentration. 

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