Single displacement
Consider the third reaction of activity 16.2. There zinc (Zn) reacts with copper sulphate and forms zinc sulphate, setting copper (Cu) free.
zinc + copper sulphate → zinc sulphate + copper
Zn + CuSO4 → ZnSO4 + Cu
Single displacement reaction
Reactions in which an element displaces another element from a compound, taking over its place and forming a different compound, are called single displacement reactions.
A + BC → AC + B
Three more examples
magnesium + copper sulphate → magnesium sulphate + copper
Mg + CuSO4 → MgSO4 + Cu
magnesium + hydrogen chloride → magnesium chloride + hydrogen
Mg + 2HCl → MgCl2 + H2
potassium bromide + chlorine → potassium chloride + bromine
2KBr + Cl2 → 2KCl + Br2
How to spot one
If there is a lone element on one side and a different lone element on the other, it is a single displacement. The two elements have traded places.
Not every element can displace every other, though — only a more reactive one can. That is what the activity series in section 16.4 tells us.