氢氧化钠滴入酚酞溶液变红 为什么一段时间后红色会消失??

2025-03-17 16:55:28
推荐回答(2个)
回答1:

酚酞是一种弱有机酸,在pH<8.2的溶液里为无色的内酯式结构,当pH>8.2时为红色的醌式结构。酚酞的醌式或醌式酸盐,在碱性介质中很不稳定,它会慢慢地转化成无色羧酸盐式;遇到较浓的碱液,会立即转变成无色的羧酸盐式。所以,酚酞试剂滴入浓碱液时,酚酞开始变红,很快红色退去变成无色。 http://zhidao.baidu.com/question/2297040.html?an=0&si=1
满意请采纳

回答2:

氢氧化纳将酚酞氧化至无色

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