35酸碱指示剂 甲基橙 Methyl Orange(MO)pK2=34 ( CH3)2N NN/S○顿 4.4 OHH+ 4.0橙 (CH3)2N =N—N 红 3.11 3.5 酸碱指示剂 甲基橙 Methyl Orange (MO) pKa=3.4 (CH3 )2N— (CH3 )2N= —N=N— H =N—N— —SO3 - —SO3 - OH- H+ + 4.4 黄 红 3.1 4.0橙