Dosage is the amount of chemical applied, demand is the amount used up, what is the amount remaining after reacting with demand?

Dosage is the amount of chemical applied, demand is the amount used up, what is the amount remaining after reacting with demand?

• A. Residual
• B. Surplus
• C. Balance
• D. Solution

Answer: (D)

When a chemical is dosed into water, some of it is consumed by reactions with substances in the water—this is the demand. The portion that remains active after those reactions is the residual. This residual tells you how much of the chemical is still available to continue working, such as continuing disinfection or pH adjustment. So, the term that describes the amount left after reacting with demand is residual. The word solution would refer to a dissolved mixture, not the leftover quantity of chemical after the water has used up part of it. A balance or surplus describes other ideas (a difference or extra beyond what’s needed), but the standard term for what’s left after reaction is residual.

When a chemical is dosed into water, some of it is consumed by reactions with substances in the water—this is the demand. The portion that remains active after those reactions is the residual. This residual tells you how much of the chemical is still available to continue working, such as continuing disinfection or pH adjustment. So, the term that describes the amount left after reacting with demand is residual. The word solution would refer to a dissolved mixture, not the leftover quantity of chemical after the water has used up part of it. A balance or surplus describes other ideas (a difference or extra beyond what’s needed), but the standard term for what’s left after reaction is residual.