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氰酸鉀含量的測定,在无杂质干扰的情况下,一般采用Volhard銀量法,但氰酸鉀多由碳酸鉀与脲素作用而制取,过程中需加热至熔融,产生的碳酸銨全部揮发,主要杂质是未作用的碳酸鉀。由于碳酸鉀的存在,簡单的Volhard法就不适用,必需加以适当的改进,或采取其他方法(保证碳酸根存在时不影响結果的准确性),才能弥补这一缺陷。普通采取加入硝酸鋇溶液的办法,将碳酸根沉淀为碳酸钡,再加入过量的硝酸銀,使氰酸根沉淀为氰酸銀,与碳酸鋇一起过滤,但碳酸銀与碳酸鋇的溶解度比較接近(S_A_(g2)CO_3:
Determination of potassium cyanate content, in the absence of impurities in the case of the general use of Volhard silver volume method, but more potassium cyanate by the action of potassium carbonate and urea system, the process needs to be heated to melt, the resulting ammonium carbonate all Volatile, the main impurity is unused potassium carbonate. Due to the presence of potassium carbonate, the simple Volhard method is not applicable, must be properly improved, or take other methods (to ensure that the existence of carbonate does not affect the accuracy of the results), to make up for this shortcoming. Ordinary to join the barium nitrate solution, the carbonate precipitated as barium carbonate, then add an excess of silver nitrate, the cyanate precipitation of silver cyanate, and barium carbonate together with the filter, but the solubility of silver carbonate and barium carbonate is relatively close (S_A_ (g2) CO_3: