Preparation and Standardization of 0.1 N Hydrochloric Acid

Описание: Neutralization of hydronium or hydroxide ion to form water is widely used as the basis for volumetric determinations of acids, bases and salts of weak acids. The reaction is characterized by a rapid change in pH near the equivalence point, a change that is readily detected by an acid-base indicator. Neutralization titrations are performed with standard solutions of strong acids or strong bases. A standard solution (or standard titrant) is a reagent of exactly known concentration.
Preparation and Standardization of 0.10 N HCl solution
1) Boil 500 mL of distilled water and then cool it. Use this distilled water to prepare 250 mL of 0.1 N (Approx.) HCl solution using 2.1 mL of concentrated hydrochloric acid.
2) Transfer 0.4900 to 0.5100 gm of dried sodium carbonate (Na2CO3) into a 100 mL volumetric flask. Dissolve the salt in 50 mL of distilled water and then volume adjusted to 100 ml with distilled water.
3) Transfer 10 ml sodium carbonate solution to conical flask and add 1 to 2 drops of methyl orange indicator.
4) Titrate the solution with hydrochloric acid solution until color change from orange to pink and persists at least 30 seconds.
5) Repeat the titration with another replicate.
6) Calculate the normality of the HCl solutions using formula N1V1=N2V2.