测定肼的方法研究

Study on determination of hydrazines by volumetric methods

研究了测定肼的两种方法——直接氧化法和络合物法。对直接氧化法研究表明,在pH1～12范围内,当氧化剂与肼的当量比值≥1.12时,氧化反应都能瞬时定量地完成。对络合物法研究发现,在pH1～12范围内,当高碘酸钠与肼的摩尔比>2时,1mol的肼将瞬时地还原2mol的高碘酸钠成对应的碘酸盐。实验还发现,在pH1～3范围内,钼酸铵、钼酸钠和钨酸钠都能与高碘酸盐形成稳定的mol比值为6的络合物,而且都不与碘酸盐络合,因此可用碘量法测定。两种方法均快速、准确及重复性好。络合物法特别有利于微量肼的测定。

Both direct oxidizing method and complexing method were used to determine hydrazines. For the former method, tie experiment proved that when the normal ratios between IO_3or IO_4and hydrazines were≥1. 12,hydrazines may be oxi- dized quantitatively. For the latter, when the mole ratios between IO_4and hydrazines are≥2, one mole hydrazines may be oxidized immediately to form two moles of IO_3. It was discovered that one of the three salts, ammonium molybdate, sodium molybdate and sodium tungstate, may react with IO_4 to form the stable complexes with a mole ratio of 6:1 at pH1-3. But IO_3did not form any stable complex with them so it can be titrated iodometrically. The two analytical methods are highspeed, precise and reproducible.