Analysis of Acidic Bright Tin Plating Solution

a. Determination of stannous content. See the determination of stannous content in tin-lead plating bath

b. Determination of sulfuric acid content. The following reagents are required:

1) 1 mol/L NaOH (40.0 g/L).

2) 4% ammonium oxalate. Dissolve 4 grams of ammonium oxalate in 96 milliliters of distilled water.

3) Methyl red indicator. Dissolve 1 g of methyl red indicator powder in 50 ml of isopropanol and 50 ml of distilled water.

Analysis method:

1) Use a pipette to draw 5 ml of the solution into a 250 ml Erlenmeyer flask.

2) Add 50 ml of 4% ammonium oxalate solution.

3) Add 20 drops of methyl red indicator.

4) Titrate with 1 mol/L NaOH until the color turns to yellow at the end point.

Calculation:

1 ml of 1 mol/L NaOH=0.0490 g/L H2SO4

ml NaOH with a concentration of 1 mol/L×9.8=g/L H2SO4

ml NaOH with a concentration of 1 mol/L×1.31=oz/gallon H2SO4