Reagents
7.1 Standard chloroplatinate solution: Dissolve 1.246 g potassium chloroplatinate,
K2PtCl6,(equivalent to 0.500 g metallic Pt)and(1)g crystalline cobaltouschloride,
CoCl2.6H2O,in distilled water containing 100 mL of conc.HCl.
Dilute to 1000 mL with distilled water. This standard solution is defined as 500 ADMI color units.
7.2 Sulfuric acid, concentrated.
7.3 Sodium hydroxide, 10 N: Dissolve 40 g of sodium hydroxide in 80 mL ofdistilled water. Cool to room temperature and dilute to 100 mL with distilled water.