A reaction in which a single element replaces an element that is part of a compound
is called a single displacement reaction or a substitution reaction. In this reaction, the single element reacts with the compound to form a new compound, while the displaced element is released as a free element. The general equation for a single displacement reaction can be represented as follows:
A + BC → AC + B
In this equation, A is the single element that replaces the element B in the compound BC. The reaction results in the formation of a new compound AC and the release of the element B. The reaction only occurs if A is more reactive than B in terms of their positions in the reactivity series. This type of reaction is commonly observed in various chemical reactions, such as the reaction of metals with acids or the displacement of hydrogen in water by more reactive metals.