In chlorine testing, a pink color indicates chlorine is present using which method?

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Multiple Choice

In chlorine testing, a pink color indicates chlorine is present using which method?

Explanation:
In chlorine testing, the pink color comes from the DPD method. DPD stands for N,N-diethyl-p-phenylenediamine. When chlorine is present, it oxidizes the DPD reagent to form a pink dye, and the intensity of that pink grows as the chlorine concentration increases. This makes the test a straightforward colorimetric readout—you compare the sample’s pink shade to a chart or measure with a photometer. Other methods don’t produce this same pink result. OTO (a different reagent) gives a yellow color when chlorine is present, not pink. Amperometric methods use an electrochemical sensor and don’t rely on a color change at all. Titration methods involve a redox reaction with an indicator and have a different endpoint appearance, not the pink color tied to DPD.

In chlorine testing, the pink color comes from the DPD method. DPD stands for N,N-diethyl-p-phenylenediamine. When chlorine is present, it oxidizes the DPD reagent to form a pink dye, and the intensity of that pink grows as the chlorine concentration increases. This makes the test a straightforward colorimetric readout—you compare the sample’s pink shade to a chart or measure with a photometer.

Other methods don’t produce this same pink result. OTO (a different reagent) gives a yellow color when chlorine is present, not pink. Amperometric methods use an electrochemical sensor and don’t rely on a color change at all. Titration methods involve a redox reaction with an indicator and have a different endpoint appearance, not the pink color tied to DPD.

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