【单选题】【消耗次数：1】
测定工业用水中的总硬度时，用氨性缓冲溶液调节水样pH为（）。
①
9
②
10
③
12
④
13
参考答案：
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【多选题】
选择缓冲溶液时应注意
①
所选用的缓冲溶液不能与反应物、生成物发生作用
②
选择适当缓冲对，使缓冲容量接近极大值
③
选择适当的总浓度，浓度一般在0.05-0.2mol/L之间
④
最后用pH计加以校准
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