Preparation of Magnesium Perchlorate

Transfer the magnesium perchlorate crystals into a porcelain crucible and dehydrate the salt by heating it in a drying cabinet at 

230 °C. How can you make sure that dehydration has terminated Cool the preparation in a desiccator over calcium chloride and transfer it into a previously weighed dry jar with a good ground-glass stopper. Weigh the jar with the preparation and calculate the yield in per cent. 

At present, the complexonometric method of determining water hardness is being widely used. This method is very sensitive and simple to use. It is based on the ability of the disodium salt of ethylenedinitrilotetraacetic acid (EDTA or complexon) 

This method is used for water with a varying salt content, but with a view to the weakly alkaline reaction in the solution in titration, one should never have a total calcium and magnesium ion concentration in a water sample exceeding 0.5 mg-equiv/litre. There- 

When the water being studied contains no magnesium ions, which occurs very rarely, the determination is possible only when a definite amount of magnesium ions is added to the volume of water measured for titration. This amount must then be subtracted from the results of the determination. 

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