抄録
Phenol sulphonic group compounds contained as additional agents to the plating bath is usually determined by gravimetric or photo-colorimetric method. But such methods are too troublesome to be practiced actually.
Therefore, a more convenient method of titrating with alkaline solution is worked out by the present study.
For example, the determination of crezol sulphonic acid in acidic tin plating bath is as follows:
1. Pipette a 5cc sample into a 250cc erlenmeyer flask.
2. Add 50cc of distilled water.
3. Add a few drops of methylorange and thymolphthalein.
4. Titrate with standard N/5 sodium hydroxide solution until a blue color is obtained.
The crezol sulphonic acid in g/l equals:
{(CCNaOH required until a blue color is obtained)-(CCNa OH required until a yellow color is obtained)}×37.8{normality of NaOH}
