Final answer:
When silver tarnishes, a single replacement reaction occurs, during which silver is replaced by sulfur atoms, forming silver sulfide and changing the oxidation state of the silver.
Step-by-step explanation:
When silver tarnishes, a single replacement reaction happens. This is because the silver metal reacts with sulfur, commonly found in traces in the air or from certain foods like eggs, and undergoes a reaction where the silver is replaced by sulfur atoms, forming silver sulfide.
During this process, the oxidation state of the silver changes, which is another characteristic of a single replacement reaction. Other possible reaction categories could include synthesis, decomposition, double replacement, and combustion, but these do not accurately describe the tarnishing of silver. In a synthesis reaction, multiple substances combine to form a single new substance, while in decomposition, a single compound breaks down to form multiple new substances. Combustion typically involves a substance reacting with oxygen to produce heat and light.
The tarnishing of silver thus illustrates an oxidation-reduction, or “redox” reaction, encompassing aspects of a single replacement reaction in which the element sulfur replaces the silver in a compound, altering the silver's oxidation state in the process.