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While you were performing titration curves (i.e. Weak Acid titrated by Strong base), you used one of the following pH indicator. Besides determining the pH curve, you determined the pH where the pH indicator changed color (called the endpoint of the pH indicator). Please get together will the other groups and make a table of all the pH indicators and their endpoint. So the table should have columns including pH indicator name, color change, pH of endpoint, Ka.
The pH indicators are:
- Bromothymol blue
- Methyl orange
- Thymol blue
- Bromocresol Green
- Phenollphthalein
- Phenol Red
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Questions (to be answered in Question section of lab report)
1. Explain how the structure of the pH indicator determines the color of the indicator at the different pH conditions.
2. Explain including using mathematics that most of the pH indicator change from one color to another in approximately 1 unit of pH.
3. Determine the Ka of each of the pH indicators (if needed use the simple average of the pH range as the endpoint).
4. Explain how to determine the appropriate pH indicator for a given titration.