indicators Flashcards
1
Q
what is a pH indicator
A
compound that undergoes colour change in a solution over a specific range of pH values.
indicators reveal when its acidic, basic or alkaline
are usually weak acids or weak bases that do not change pH
2
Q
how does a indicator work when it becomes more acidic
A
Hln + H20 – h30+ + ln-
if ph of solution with indicator become more acidic
- h30 conc increases
- backwards rr increase
- more Hln produced
- Hln has the acid colour, so acid colour is observed
3
Q
how does a indicator work when it becomes more basic
A
Hln + H20 – h30+ + ln-
-h30 conc decreases
- forwards rr increase
- more ln- is produced
-ln- has the base colour, so base colour is observed
