Acid-base titration Tamil revision mind map: the distinction between equivalence point and end point, the four types of titration curve for strong and weak acid-base combinations with their equivalence-point pH and steep-region characteristics, the acid-base indicator equilibrium HIn reversible H-plus plus In-minus where pH equals pKIn at the colour midpoint, the colour-change range of approximately pKIn plus or minus one with common indicators, the rule for choosing an indicator whose range must fall inside the steep region, and the double-indicator method for analysing sodium carbonate and bicarbonate mixtures.