在用 K2Cr2O7 法测定 Fe 时,加入H3PO4的主要目的是 ( ) -题库考试答案搜索网

在用 K2Cr2O7 法测定 Fe 时,加入H3PO4的主要目的是 ( )

单选题

2021-09-01 23:52

A、提高酸度,使滴定反应趋于完全
B、提高化学计量点前Fe3+/Fe2+ 电对的电位,使二苯胺磺酸钠不致提前变色
C、降低化学计量点前Fe3+/Fe2+电对的电位,使二苯胺磺酸钠在突跃范围内变色
D、有利于形成 Hg2Cl2 白色丝状沉淀

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正确答案

C

试题解析

标签：青书学堂齐齐哈尔医学院分析化学

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