18.15 pH Indicators (Video)
- Page ID
- 342573
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Video Topics
This video discusses pH indicator and how they are used.
Indicators are usually weak acids
The acid and its conjugate base have different colors
HIn(aq) + H2O(l) ↔ H3O+(aq) + In-(aq)
By le Chatelier's principal
Adding H+ shifts the equilibrium to the left. The acid color appears.
Adding -OH reduces H3O+ and the equilibrium shifts right. The base color appears.
When {HIn} = {In-} and intermediate color appears.
This occurs when pH = pKa.
The color change occurs of a range of pH = pKa +/- 1
Acid color pH < pKa -1
Intermediate color pH = pKa
Base color pH > pKa + 1
Link to Video
pH Indicators: https://youtu.be/1IqzUa5lABs
Attribution
-
Prof. Steven Farmer (Sonoma State University)