Platinum molten, density

A cell with a capacity of 1 L was made of mild steel. An amorphous carbon rod (diameter 25 mm length 15 cm) was used as anode, the inside wall of the cell as cathode and a platinum wire was used as reference electrode. The anode compartment of the cell was separated from the cathode compartment by a skirt of steel welded to the cell cover. The anode gas was passed through a tube filled with tablets of NaF to absorb anhyd HF gas and then led to a gas sampler. Fluorine was detected with K.I soln. After the starting material was added into the molten KIIF2/HF salt, the electrolyte was pre-electrolyzed at a low current density until NF2 was detected, and then current efficiency of each product and polarization curves by galvanostatic or potential sweep method were determined (Table 1). At optimum conditions the current efficiency of NF3 was 55%. 

The density of melts is usually measured by weighing a platinum body in air and in the melt. Gas bubbles adhering to the body are the main source of errors involved in the method. It is also possible to measure directly a volume of the melt (Volarovich and Leonteva, 1936) or with high-density glasses to weigh the melt in a platinum vessel in molten salts, e.g. NaCl (Hanlein, 1932). 

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