7. Reagents
7.1 Alcohols, refined, ethyl or isopropyl.
Isopropyl alcohol (99% grade) conforming to Specification D770, or 190 proof ethyl alcohol conforming to formula No. 3A of the U.S. Bureau of alcohol, Tobacco and Firearms is suitable for use as the solvent. The use of methyl alcohol is not recommended.
7.2 Phenolphthalein Indicator Solution (10 g/L) Dissolve 1 g of phenolphthalein in ethyl or isopropyl alcohol (see note 1) and dilute to 100 mL with the alcohol.
7.3 Sodium Hydroxide, Standard Solution (0.05 N) Prepare and standardize a 0.05 N sodium hydroxide (NaOH) solution (Note 2) in accordance with the preparation and Standardization of Solutions, Precision and Bias, Preparation of 50% of NaOH Solution and of Standard Solutions, and Standardization sections of Practice E200.