有色化學實驗-溴甲酚綠在水/有機相的分配 Colorful Chem Exp - The Partition of Bromocresol Green between

(A)
乙酸乙酯 (EA) 和 水
ethyl acetate (EA) & water
(B)
加入少許溴甲酚綠粉末，不搖晃或攪拌
a tiny amount of powder of bromocresol green being added, without shaking or stirring
(C) 
搖晃後，溴甲酚綠溶解並分布於水層
after shaking, bromocresol green dissolving & distributing in the water layer
(D) 
加入數滴鹽酸，不搖晃或攪拌。溴甲酚綠變色
adding a few drops of HCl, without shaking or stirring, the color of bromocresol green changed
(E) 
搖晃後，酸性態溴甲酚綠移至有機（EA）層
after shaking, bromocresol green (acidic form) moving into the organic (EA) layer

自己覺得這是個不錯的「酸鹼指示劑的酸性/鹼性型態性質可能大不同」實例。
溴甲酚綠的鹼性型態（弱酸至鹼性）為陰離子，傾向分配在水層，而酸性型態為電中性，傾向分配在中等極性EA有機層
It's a good example about "the acidic & basic forms of a pH indicator may be so different".
The basic form (> pH 5.5) of bromocresol green is an anion and tends to be in the water. But its acidic form (< pH 4) is electrically neutral and makes it to be in the organic layer.