34634
Accession Number
33124
Title Of Article Chaper
Tarnish-removing dips for silver, gold and copper
Title Of Journal Book
Electroplating and Metal Finishing
Volume
6
Pages
371-373
Literature Type
Serial
Literature Level
Analytic
Abstract
A typical tarnish-removing dip contains by wt.: thiourea 8, HC1 (37.5% concn.) 5.1, H<sub>2</sub>O-sol. perfume 0.3, detergent and (or) wetting agent 0.5 and H<sub>2</sub>O 86.1%. Benzaldehyde may be added to mask the H<sub>2</sub>S odor, and it is rendered H<sub>2</sub>Osol. by adding a nonionic detergent. This type works according to the equation: Ag<sub>2</sub>S+2H<sup>+</sup> +2<i>nCS(NH<sub>2</sub>)<sup>2</sup> = 2Ag (CS(NH<sub>2</sub>)<sub>2</sub>1n+H<sub>2</sub>S. The capacity to dissolve Ag<sub>2</sub>S is shown by: (T -- 6X)<sup>6</sup> (A -- 2X) <sup>2</sup> /X<sup>3</sup>=8.44 where T is thiourea concn., and X is amt. of Ag<sub>2</sub>S, both in moles/1., and A is acidity -- AATA
pub_id
34634