A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.
(a) Why do silver articles turn black when kept in the open for a few days? Name the phenomenon involved. (b) Name the black substance formed and give its chemical formula.
$2Ag + H_2S →Ag_2S + H_2$
(a) Silver reacts with H2S present in the atmosphere to form a black colour compound Silver Sulphide. This phenomenon is called corrosion.
(b) The black colour compound formed is Silver Sulphide (Ag2S).
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