Double displacement reaction
In a chemical double displacement reaction or double replacement, metathesis, or ion exchange two compounds swap ions, effectively displacing each other to form two new compounds, thus the name. The general formula is Ax + By → Bx + Ay. For example:
One of the compounds formed is usually a precipitate, an insoluble gas that bubbles out of the solution, or a molecular compound, usually water.
A neutralization reaction is a specific type of double displacement reaction. Neutralization occurs when equal amounts of acid react with equal amounts of a base. A neutralization reaction creates a solution of salt and water. E.g.: