Final answer:
The reaction 2AgBr+light→2Ag+Br₂ is both a decomposition and a redox reaction, involving electron transfer and breakdown of a compound, and it is also specifically classified as a photochemical reaction.
Step-by-step explanation:
The reaction 2AgBr+light→2Ag+Br₂ is an example of a decomposition reaction where silver bromide (AgBr) breaks down into silver (Ag) and bromine (Br₂) upon exposure to light. This type of reaction is also known as a photochemical reaction, which is a subset of decomposition reactions that specifically require light to proceed. Additionally, as electrons are transferred from bromine to silver, this is also a redox reaction. Silver ions (Ag+) gain electrons to become silver atoms (Ag), and bromine atoms lose electrons to form bromine molecules (Br₂), showcasing the reduction and oxidation processes respectively.
In the general notation AB → A + B, this represents a decomposition reaction. Examples such as 2K(s) + Br2(l) → 2KBr(s) or NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s) showcase redox reactions, where electron transfer is evident. In the reaction 2Ca(s) + O₂(g) → 2CaO, calcium (Ca) loses electrons (oxidation) and oxygen (O₂) gains electrons (reduction).
Considering energy changes in reactions, reactions that absorb energy are endergonic, while those that release energy are exothermic. For instance, 2H₂(g) + O₂(g) → 2H₂O(l) + 135 kcal releases energy, thus it's exothermic, while N₂(g) + O₂(g) + 45 kcal → 2NO(g) requires energy input, making it endergonic.