Sulfate in Chromium Plating Baths

Prove InstrumentsTurbidimetric determination subsequent to acid mineralisation

Sample Preparation

Place 2 ml bath sample in a 250-ml beaker, add 10 ml 37 % hydrochloric acid, cover with a watch glass and boil gently - in a fume cupboard - until all the Cr(VI) has been reduced to Cr(III). The sample will become dark green due to the effect of the released chlorine. Continue heating until acid fumes cease and a syrupy residue is left. Dissolve the residue in about 30 ml water for analysis and transfer the solution to a 50-ml volumetric flask. Adjust the pH to 8.5 - 9.5 with ammonia solution, checking with pH-indicator strips. Make up to the mark with water for analysis and mix. Filter off the precipitated chromium (as Cr(OH)3) and adjust the pH of the clear filtrate to pH 7 - 8 with as little as possible 25 % hydrochloric acid (volume error!).

Analysis

Determine with the below mentioned test kits.

Calculation

Sulfate content in mg/l SO4 = analysis value in mg/l SO4 x 25

Materials

     

Product 100617 is not compatible with Move 100.