indicator error

Question

Indicator error minimized by selecting indicator whose transition range:

RankGuru · Accepted Answer

1. **Ideal Case**: The color change should happen exactly at the equivalence point.
2. **Systematic Error**: If the indicator changes color too early or too late, the volume measured is incorrect. This is known as **indicator error**.
3. **Selection Rule**: Calculate or determine the $pH$ at the equivalence point. Then, choose an indicator such that the equivalence $pH$ lies comfortably within the indicator's **transition interval** ($pKa \pm 1$).
4. **Example**: In a strong acid - strong base titration, since the $pH$ changes sharply from $4$ to $10$, many indicators like methyl orange or phenolphthalein work with minimal error.

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indicator error

Select the correct option: