Final answer:
Silver oxide is photosensitive and undergoes a redox reaction upon light exposure, reducing silver ions to metallic silver and liberating oxygen gas. It serves as a catalyst in nucleophilic substitutions by acting as a Lewis acid. The correct decomposition formula under light is 2Ag2O → 4Ag + O2.
Step-by-step explanation:
When silver oxide is exposed to light, it decomposes because it is photosensitive; the reaction that represents this process is not shown in your equation.
Photosensitivity is due to the ability of silver oxide to absorb light energy and undergo a redox reaction, leading to the reduction of silver ions to metallic silver and the release of oxygen gas.
The correct balanced equation for the decomposition of silver oxide under light is:
2Ag2O → 4Ag + O2
Silver oxide acts as a catalyst in nucleophilic substitution reactions because it can accept electrons (Lewis acid), facilitating the reaction process. The photosensitivity of silver oxide is a separate property that plays a role in its decomposition rather than its catalytic activity.
Refining Redox
During the refining of silver to produce dicyanoargenate(I) ions, oxygen must be present to serve as the oxidizing agent, enabling the silver to be oxidized from the 0 oxidation state to the 1+ state.
This is due to the need for both the loss and gain of electrons in redox reactions to maintain charge balance. Oxygen, by gaining electrons, is reduced from the 0 oxidation state to the 2- state, as in the reaction:
4Ag(s) + 8CN- (aq) + O2(g) + 2H2O(l) → 4[Ag(CN)2]-(aq) + 4OH-(aq)
Examples of Redox Reactions involving Silver Compounds