General Chemistry Question

[aymar]

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This is a question from McGraw-Hill's new 500 question gen chem book:

Light induces the following rxn in some photographic paper:
AgI(s)--->Ag(s)+I(s)

What type of rxn is this? Answer: reduction rxn


- In the answer explanation, it says that there has been no change in the iodide ion, but that silver has gone from Ag+ to solid silver by gaining an electron (reduction reaction). Why is there no change in the iodide ion if the initial compound is ionic and the iodide ends up as a lone solid as well? (aka why is it not a reduction and oxidation rxn)

 

[popopopop]

AgI(s) + e- --->Ag(s)+ I- (s)

 

[Cawolf]

Are you sure that the reaction is as you've written?

 

[vivatix]

AgI -> Ag(s) + I(s)

Ag in AgI is +1 and Ag(s) is o -> reduction
I in AgI is -1 and I(s) is -1 -> no change

 

[popopopop]

The key seems to be that the light reduces silver ion down to neutral. That's all I can really find for an explanation.

 

[JoeCaputo]

If silver is reduced, what is the reducing agent? The photons?

 

[Giovanotto]

nvm