In this video from www.youtube.com/@STI-SurfaceTechnology we share the simple way to titrate an electroless nickel plating bath to determine its sodium hypophosphite concentration. This method is one of the best practices from our state of the art plating shop dedicated to electroless nickel and composite electroless nickel, which features our One-Plate single component electroless nickel solutions.
The complete procedure is also described below:
ANALYSIS
The reagents needed for the Sodium Hypophosphite analysis are: 0.1 N Iodine/Iodide Solution, or 0.1 N iodide/iodate solution, 0.1 N Sodium Thiosulfate solution, and 50% HCl or 6 N HCl.
PROCEDURE
1. Pipette a 5.0 ml sample of solution into a 250 ml Erlenmeyer flask.
2. Add 25 ml of 6 N HCl via graduated cylinder.
3. Pipette 50.0 ml of 0.1 N Iodine/Iodide solution into the flask and swirl to mix.
4. Stopper flask and store in the dark for a minimum of 30 minutes. If ambient is below 65˚F, allow 60 minutes reaction time in the dark.
5. Titrate with 0.1 N Sodium Thiosulfate to clear colorless endpoint and record the number of ml titrated.
CALCULATION
Sodium Hypophosphite concentration in g/l = (ml of 0.1 N Iodine/Iodide - ml of 0.1 N Sodium Thiosulfate) X (1.05)
NOTE
When analyzing concentrated solutions of Sodium Hypophosphite, it is necessary to dilute the sample by pipetting exactly 5 ml of the concentrated solution into a 100 ml volumetric flask and diluting it to exactly 100 ml then mixing the diluted sample well. Now you can proceed with the above analysis but remember to multiply the calculation results by 20 to compensate for the dilution of the concentrated sample to obtain the correct Sodium Hypophosphite concentration of the unknown solution.
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