The comparative breakdown of passivity of tin by fluorides and chlorides interpreted through the ‘law of matching affinities’ concept

• Breakdown of passivity of tin by fluorides.
• Kinetics of attack by fluoride is much slower than with chloride.
• Predominant halide-dependent mechanism of attack conditioned by anion-specific hydration properties.

The comparative breakdown of passivity of tin by fluorides and chlorides highlight the significant slower kinetics of attack by the kosmotrope fluoride when compared to the chaotrope chloride at pH 5.7 and 10. The origin of this difference is ascribed to the predominant halide-dependent mechanism of attack, pitting with chlorides and film thinning with fluorides, which is conditioned according to the anion-specific hydration properties.