Which water testing indicator would be used to assess free chlorine levels?

Which water testing indicator would be used to assess free chlorine levels?

• A. Phenol Red
• B. DPD
• C. Litmus
• D. pH Indicator

Answer: (B)

The choice of DPD (N,N-diethyl-p-phenylenediamine) as the indicator for assessing free chlorine levels is appropriate due to its specific chemical reaction with chlorine. When DPD is added to a water sample containing free chlorine, it changes color based on the concentration of chlorine present. This colorimetric method allows for the quantification of free chlorine levels, making it a reliable indicator in water testing for disinfectant effectiveness in swimming pools and drinking water supplies. Other indicators, while useful for different purposes, do not specifically measure free chlorine levels. For instance, Phenol Red is primarily utilized for measuring pH levels, Litmus is a general pH indicator, and a pH Indicator measures acidity or alkalinity but does not provide direct information about chlorine concentration. Therefore, DPD’s specificity and sensitivity make it the ideal choice for assessing free chlorine levels in water testing scenarios.

The choice of DPD (N,N-diethyl-p-phenylenediamine) as the indicator for assessing free chlorine levels is appropriate due to its specific chemical reaction with chlorine. When DPD is added to a water sample containing free chlorine, it changes color based on the concentration of chlorine present. This colorimetric method allows for the quantification of free chlorine levels, making it a reliable indicator in water testing for disinfectant effectiveness in swimming pools and drinking water supplies.

Other indicators, while useful for different purposes, do not specifically measure free chlorine levels. For instance, Phenol Red is primarily utilized for measuring pH levels, Litmus is a general pH indicator, and a pH Indicator measures acidity or alkalinity but does not provide direct information about chlorine concentration. Therefore, DPD’s specificity and sensitivity make it the ideal choice for assessing free chlorine levels in water testing scenarios.