What is the formula to calculate breakpoint chlorination?

The formula to calculate breakpoint chlorination is based on the need to achieve a certain residual free chlorine level that is effective in overcoming combined chlorine. Breakpoint chlorination is the process of adding enough chlorine to oxidize combined chlorine to free chlorine and is crucial for maintaining water quality.

The correct approach states that you need to multiply the combined chlorine (CC) level by a factor of 10 to ensure that you have enough chlorine added to eliminate the combined chlorine effectively. This reflects the chemical nature of chloramines and the amount of free chlorine required to break down those forming compounds.

Calculating breakpoint chlorination involves determining how much chlorine is necessary to achieve a balance where all the combined chlorine is effectively converted back to free chlorine. This factor of 10 is derived from practical experience in aquatic facilities, indicating that for every part of combined chlorine, a significant amount of chlorine must be added to reach the breakpoint.

Other choices do not accurately reflect the established practices for calculating the required chlorination level. The formula suggesting to multiply by 5 would not provide a sufficient dose for effective chlorination, while adding free chlorine (FC) and total chlorine (TC) does not offer a clear method for overcoming combined chlorine. Dividing combined chlorine by 2 does not align with