Acid base indicators are either weak organic acids or weak organic bases. Indicator change colour in dilute solution when the hydronium ion concentration reachesa particular value. For example, phenopthalein is a colour less substance in any aqueous solution with a pH less than 8.3 in between the pH range8.3 to 10, transaction of colour (colourless to pink) takes place and if pH of solution is greater than 10, then solution colour is dark pin. Considering an acid indicator HIn, base In^(-) can be represented as : HIn hArr H^(+) + In^(-) acidic form basic form pH of solution can be computed as : pH = pK_(In) + "log" ([In^(-)])/([HIn]) In general, transition of colour takes place in between the pH range pK_(In) +-1 Select the correct statement among the following

Acid base indicators are either weak organic acids or weak organic bas

1.	Acid base indicators are either weak organic acids or weak organic bases. Indicator change colour in dilute solution when the hydronium ion concentration reachesa particular value. For example, phenopthalein is a colour less substance in any aqueous solution with a pH less than 8.3 in between the pH range8.3 to 10, transaction of colour (colourless to pink) takes place and if pH of solution is greater than 10, then solution colour is dark pin. Considering an acid indicator HIn, base In^(-) can be represented as : HIn hArr H^(+) + In^(-) acidic form basic form pH of solution can be computed as : pH = pK_(In) + "log" ([In^(-)])/([HIn]) In general, transition of colour takes place in between the pH range pK_(In) +-1 Select the correct statement among the following
Answer» In the complete IONISATION of indicator its `pH = pK_(In)` Methyl orange (working range : `3.1` to `4.4`) is a SUITABLE indicator for weak acid and strong base Bromothymol blue (working range of `6.0` to `7.6`) is a good indicator for titration of `HCl` and `NAOH` Thymal blue (working range `1.2` to `2.8` ) is good indicator for titration of `100 ml` of `0.1 M NH_(4)OH(pK_(b) = 4.74)` and `0.1 M HCl`. SOLUTION :N//A