see the attachment

the yellow color is generated by the quinone type structure of p-nitrophenol when it dissociates.
   The increase of hydronium concentration pushes the equilibrium to shift to the left side where the phenol type dominates, whose structure generates no visible absorption and therefore colorless.



【 在 yzwen.bbs@bbs.zju.edu.cn (嘀笃) 的大作中提到: 】
:  对硝基苯酚为黄色，容于水后，加一滴1：1盐酸居然变为无色溶液，望各位指点一下?:   ?
--
FROM 131.193.235.*