【单选题】听力原文:W: Hi, Honey. I'm sorry, I've some bad news to tell you. The management is making cuts, and I've lost my job. M: Oh, dear! That's terrible. But you didn't like that job very much anyway. Maybe th...
【简答题】实验室常用邻苯二甲酸氢钾(KHC 8 H 4 O 4 )来标定氢氧化钠溶液的浓度,反应如下: KHC 8 H 4 O 4 +NaOH=KNaC 8 H 4 O 4 +H 2 O。邻苯二甲酸氢钾溶液呈酸性,滴定到达终点时,溶液的pH约为9.1。 (1)为标定NaOH溶液的浓度,准确称取一定质量的邻苯二甲酸氢钾(KHC 8 H 4 O 4 )加入250mL锥形瓶中,加入适量蒸馏水溶解,应选用_____...