What is the titrant used in the method?

• A. 0.4 N NaOH
• B. 0.1 N HCl
• C. 0.5 N KOH
• D. 1 N NaOH

Answer: (A)

In a titration, the titrant is the standard solution you add in known amounts to react with the analyte. For this method, a strong base is used to neutralize the sample’s acidic components, and sodium hydroxide is chosen because it fully dissociates to provide a reliable and predictable supply of OH- ions, which drives the reaction cleanly to the endpoint.

The concentration of the titrant, 0.4 normal, is selected to give a practical titration: enough base is added to reach the endpoint within a reasonable volume for accurate measurement, while not being so concentrated that small volume errors cause large shifts in the calculated result. Using a much stronger titrant (like 1 N) would mean very small volumes and higher susceptibility to measurement error; a much weaker titrant (e.g., 0.1 N) would require much larger volumes and could be impractical or exceed the burette’s capacity.

HCl, being an acid, would be used to titrate bases, not to act as the base titrant for this method. KOH could serve as a base titrant, but the procedure specifies NaOH, likely due to standardization practices and compatibility with the method’s indicators and calculations.