题目内容

已知CH3COOH（简写为“HAc”）的离解常数Ka=1.75×10-5，NH3·H2O的离解常数Kb=1.8×10-5。回答下列问题：氨水中氨含量的分析常用返滴定法，为什么通常不采用直接滴定的方法？

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We have to work hard,（）we’ll lose the chance.

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---Do you really hate Mary that much?---Yes,indeed.And I feel sorry for （） marries her.

A. whoever
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已知CH3COOH（简写为“HAc”）的离解常数Ka=1.75×10-5，NH3·H2O的离解常数Kb=1.8×10-5。回答下列问题： NH4Cl纯度的分析为什么不能用直接滴定的方法？甲醛法测定铵盐时为什么用酚酞作指示剂？

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