QC Lab - Experiment 4: Preparation and standardization of 0.1n sodium hydroxide solution

sodium hyroxide

•Also known as lye, or caustic soda

•At room temperature, it is a white crystalline odorless solid that absorbs moisture from air and dissolves into it (DELIQUESCENT)

•It is used in the manufacture of soaps, rayon, paper, explosives, dye stuff and petroleum products, etc.

secondary standard

•Chemical that has been standardized against a primary standard for use in a specific analysis (can remain stable for a long time)

properties of secondary standard

•Has less purity than primary standard

•Less stable and more reactive than primary standard

•Titrated against primary standard

procedure

•Dissolve 2.6g of Sodium hydroxide pellets in 500mL of distilled water in a volumetric flask (TITRANT)

1.Measure approximately 20mL of standardized 0.1N Sulfuric acid [from previous experiment (#3)]

2.Add 2 drops of phenolphthalein TS and titrate with Sodium hydroxide solution until the production of a permanent pink coloration

3.Calculate the normality of your standard solution

4.Label the container properly with the actual normality computed

normality

N1V1 = N2V2

sulfuric acid

primary standard (erlenmeyer) + phenolphthalein

sodium hydroxide solution

titrant (burette)

phenolphthalein

indicator

permanent pink

endpoint

more than 1 trials

trial 1 + trial 2 divided by 2