02 End point and indicators
- The end point is the point at which the neutralization reaction is just complete.
- An indicator (a substance that changes colour with the medium) shows it.
1Methyl orange
In acid
- Red
In base
- Yellow
Neutral
- Orange
2Phenolphthalein
In acid
- Colourless
In base
- Red/pink
Neutral
- Colourless
3Litmus
In acid
- Red
In base
- Blue
Neutral
- Violet
4Bromothymol blue
In acid
- Yellow
In base
- Blue
Neutral
- Green
For the titration of a strong acid with a strong base (HCl with NaOH) any of these indicators can be used, because the sharp change in pH at the end point is much wider than the transition range of the indicator.