Displacement Reactions Chemistry Displacement reactions A displacement reaction takes place when a more reactive substance displaces a less reactive substance. Displacement: Replacement or replacing. Sodium is more reactive so it burns in pure oxygen. It needs to be stored Under a layer of oil. Copper is not very reactive. It can be molded int items like coins or bells Reactivity series Most reactive More reactive substances are at the top and less reactive substances at the bottom of the table. Substances that don’t react with oxygen, water or acids (gold and silver) are called inert. The reactivity series, provides a clue on how metals will react with each other. There are two non-metals are used in displacement reactions. They are carbon and hydrogen. Less Reactive Example displacement reactions in water molecules The displacement of hydrogen by magnesium: The displacement of hydrogen by potassium: Magnesium slowly displaces hydrogen present in the water molecules. To test the product magnesium hydroxide, phenolphthalein is used as an indicator. The hydrogen present in water molecules is displaced when potassium is reacting with it. Potassium hydroxide is formed. Magnesium + water hydroxide + hydrogen Potassium + water hydroxide + hydrogen magnesium Left: magnesium in water Right: Phenolphthalein potassium Potassium reacting in water Displacement of metals Displacement of silver by copper: Displacement of copper by iron: When a copper wire is added to a solution of silver sulfate, the copper displaces the silver in the solution and the silver deposits on the wire. When an iron nail is placed in a solution of copper sulfate, the iron displaces the copper in the sulfate and the copper deposits on the nail. Copper + silver sulfate sulfate + silver Iron + copper sulfate copper copper iron sulfate + The use of displacement reactions o Displacement reactions are used in many places. o It can be used in joining two metal rails together. o It is used in tablets which are used to treat indigestion.
