stannous chloride solution

[relpub3]

I have read somewhere that it is recommended that one add a small piece of tin metal to the stannous chloride solution to extend its life.

Is this true?

Isn't it the reagent grade Stannous Chloride powder is made from a mix of tin metal and hydrochloric acid? so it already has tin in it and would not the excess tin change the chemistry of the solution.

It has been said that the solution must be made in the same way each time so if the addition of tin will not change the readings, is the addition of tin metal an acceptable procedure of making this solution a standard one?

thanks

Alberto

 

[lazersteve]

Alberto,

I find the excess tin helps extend the life of the solution. Personally, I keep a stock stannous chloride solution in a 150 mL flask and add fresh tin with heating before each use. After a week or so the additonal tin merely dissolves. If the refreshed solution does not react to a known auric chloride solution I add a small amount of HCl. Each month or so I'll discard the old solution and start over.

Powdered tin metal is not required. The tin metal can be in any form as long it's the native metal and not combined in a compound. I sell small strips of pure tin on my website. These strips may in fact extend the life of the test solution longer than the powder due to the slower rate of dissolution of the solid tin.

Steve