Final answer:
The reaction 2AlCl3 → 2Al + 3Cl2 is classified as a decomposition reaction, not a synthesis, single replacement, or double replacement reaction.
Step-by-step explanation:
The reaction 2AlCl3 → 2Al + 3Cl2 is a type of chemical reaction where a single compound breaks down into two or more simpler substances. According to the general form of a decomposition reaction, where a single compound (AxBy) breaks down to form multiple products, such as A + B, this reaction fits the description. Therefore, this reaction is a decomposition reaction. It is not a synthesis, single replacement, or double replacement reaction since it involves the breaking apart of a single reactant into multiple products without exchange of ions between two compounds.