Evidence of a chemical reaction can be seen in the formation of a new substance, as seen in the difference of the structure and color of the metals below.
A single replacement can be both endothermic and exothermic depending on the situation, which effects the change in potential energy to possibly increase or decrease.
Helpful tools in the conduction of this research would include an activity series, which would help determine the likeliness a single replacement reaction would occur.
Ex: A + BC -> B +AC where A is metal
A + BC -> C + BA where A is non-metal
Usually when two ionic solutions react to produce 2 other ionic compounds.