Analysis of potassium carbonate in cyanide plating bath

A. Take a 10 ml sample of plating bath, add about 100 ml distilled water, and heat it almost to boiling. With stirring, gradually add 15 ml 10% barium chloride or barium nitrate solution. A white precipitate will form.

Continue heating, with occasional stirring, for about an hour. Add more water if necessary. Now, let it cool, and filter it through Whatman #4, or the equivalent. Heat up about 50 ml more distilled water, and rinse the white solid in the cone with it. Take the filtrate and put it in your cyanide waste treatment system, or just add some bleach [adv: bleach/sodium hypochlorite in bulk on eBay or Amazon] to it, with good ventilation.

Transfer the filter cone, plus the precipitate, to a beaker . Add about 80 ml of water, and a few drops methyl orange [on eBay or Amazon] indication solution. Now, titrate to a red endpoint, with 1N HCl [affil links].

I do not recall the factor. With a little arithmetic, you can calculate it.

A. Here's one way:
Reagents: 1.0M HCl, 30%BaCl, methyl orange [on eBay or Amazon] indicator

Procedure: pipette [pipettes on eBay or Amazon] 10ml plating solution into a 400ml beaker [beakers on eBay or Amazon], add 200 ml DI water, and heat to just under boiling. Add 15 ml BaCl, allow the precipitate to settle, and filter through a #40 Whatman filter paper, washing with hot DI water. Transfer the paper with precipitate to a beaker, add 200 ml DI water, and pulp the paper with a stirring rod. Add 5 drops methyl orange [on eBay or Amazon] and titrate with 1.0N HCl to a pink endpoint.

g/l K2CO3= (mls HCl) x 6.9