Summary for tin plating bath analysis Discussion
Tin plating bath solution analysis is discussed for a bath containing sodium stannate, sodium hydroxide, and sodium acetate. Fotini Kiriakou asked how to determine both tin stannate and free NaOH. Onkar Kulkarni replied with a simple iodometric method for the tin stannate portion: take 5 ml of bath solution, add 5 ml concentrated HCl and 5 ml starch indicator, then titrate with 0.1N iodine; multiply the burette reading by 1.187 to get g/L of stannous. Ian Jones said he already uses a similar method for tin stannic salts but with a nickel catalyst and a 40-minute boil, and asked whether Onkar’s method is comparable. For free sodium hydroxide, hadi khosravi suggested mixing 10 ml of sample with 50 ml of 10% barium chloride and thymolphthalein, then titrating with 1N HCl to a blue endpoint; titre × 4.00 gives g/L free NaOH, with extra indicator added if precipitate absorbs it.
Q. Dear Sirs,
I am trying to find methods of analysis of a Tin Plating bath solution which consists of: Na2SnO3·3H2O = 70 gr/l, NaOH = 11 gr/l, and CH3COONa = 22 gr/l. I have to determine the concentration of Tin Stannate (Na2SnO3·3H2O) (gr/l) and Free Sodium Hydroxide(NaOH)(gr/l) in the above solution. Please, suggest methods.
Thanking in advance,
Fotini Kiriakou
Chemical Lab – Tanagra, Viotia, Greece
2004
A. Dear friend,
You have to take 5 ml of bath solution add to it 5 ml conc. HCl and 5 ml starch indicator and titrate it against 0.1N Iodine solution. Multiply B.R. by 1.187 you will get the GPL of Stannous.
Onkar Kulkarni
– Pune, Maharashtra, India
Q. Dear Onkar Kulkarni,
I use the method you suggest for the tin stannic salts but add a nickel catalyst to the tin and HCl and boil to a receiving vessel for 40 mins and titrate as your method. This is time consuming but does work; is your method comparable with mine? I will try your method out.
Many thanks,
Ian Jones
– Wrexham
Q. Dear friend
I would like to thank you for your response to the first part of my question, determination of Sodium Stannate. I would really appreciate if you or anybody else could give me a method for the second part of my question that is the determination of Free Sodium Hydroxide in the Tin Plating Solution Bath.
Thank you again,
Fotini Kiriakou [returning]
– Tanagra, Viotia, Greece
A. Dear Fotini
mix 10 ml of vat sample with 50 ml Cl2Ba (10%) and a few drops of thymolphtalein indicator. Titrate with 1N hydrochloric acid to blue end point.
Titre x 4.00 =g/l free NaOH
PS: due to absorption of the indicator by precipitate, add few extra spot of indicator a half way point of titration.
hadi khosravi
– tehran iran
Dear Hadi, thanks a lot for your response to my question. It will help me very much.
Have a good day.
Fotini Kiriakou [returning]
– Tanagra, Greece
Q. Dear sir,
What is meant by 10 Vat sample in the free alkali test you had mentioned. Please suggest; I am waiting for your response.
mahesh patil
– Thane, Maharashtra, Indian
April 14, 2015
A. Hi Manesh. Hadi surely means a 10 ml sample from the vat (tank or bath) of tin plating solution which you wish to analyze. Best of luck with it.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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