CHEM Reactivity Series

Reactivity Series

Introduction

• Gold was the first metal used by humans due to its unreactive nature.

• The reactivity series arranges metals from most to least reactive.

• Carbon and hydrogen are included in the series for reasons explained later.

• The order of reactivity is determined by reactions with cold water, steam, and dilute hydrochloric acid.

Acronym

• Please (K)

• Send (Na)

• Cats (Ca)

• Monkeys (Mg)

• And (Al)

• Cute (C)

• Zebras (Zn)

• In (Fe)

• Large (Pb)

• Heavy (H)

• Cages (Cu)

• Make (Hg, mercury)

• Sure (Ag)

• Padlocked (Pt, platinum)

Reactions with Water and Steam

• Some metals like potassium and sodium react violently with cold water.

• metal + water \rightarrow metal hydroxide + hydrogen

• Magnesium reacts less violently with cold water.

• Zinc and iron react with steam but not with cold water.

• metal + steam \rightarrow metal oxide + hydrogen

Reactions with Hydrochloric Acid

• Metals react with dilute hydrochloric acid to form a salt and hydrogen gas.

• metal + dilute hydrochloric acid \rightarrow metal chloride + hydrogen

• More reactive metals react more violently.

• Lead's reaction with hydrochloric acid is limited due to the formation of an insoluble layer of lead(II) chloride.

• Metals above hydrogen in the reactivity series react with hydrochloric acid to produce hydrogen gas.

Deducing Reactivity Order

• A more reactive metal can displace a less reactive metal from its salt solution.

• A more reactive metal can displace a less reactive metal from its oxide.

Metal Extraction

• Most metals exist in ores (oxides, sulfides, chlorides, or carbonates mixed with earth and rock).

• Extraction methods:

• Reducing the metal compound with carbon.

• Electrolysis.

• The method depends on the metal's position in the reactivity series; more reactive metals require electrolysis.

Rusting

• Rusting is the corrosion of iron, forming hydrated iron(III) oxide.

• $$iron + oxygen + water \rightarrow hydrated iron(III