Determination of Free Chlorine in Swimming Pool Water Using a Comparator

Chemistry Page

Equipment:

• Comparator
• DPD No.1 Tablets
• Sample of water

Experiment:

1. Rinse compartments of comparator with samples of water
2. Fill compartments with sample to calibrated mark
3. Add DPD No.1 tablets to each compartment and dissolve completely with a stirring rod
4. Fit lid and shake until dissolved completely
5. Compare colour of solutions to pre calibrated colours on comparator. Note concentration.

Possible Questions

1. What makes up free chlorine?

Chloric acid (HOCl) and the chlorate ion (ClO-)