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Reactivity Series of Metals

  • Last Updated : 08 Dec, 2021

The things around are either metal and non-metal, we need to differentiate between both of them, Here we need to first study the properties that make metal and non-metal different and further their reactivity. The reactivity series is a table that provides the data about the reactivity of different metals that can be used to predict whether a metal can displace another in metal reaction or reactivity of metals towards water and acids. Reactivity series is also beneficial to predict whether a displacement reaction is single or double. All the metals and non-metal have different properties with their property we can determine whether is this metal more reactive in air, water or acid. In this, we will learn about Reactivity Series and Displacement Reactions of Metals.

Displacement Reaction

Displacement reactions are significant chemical reactions in chemistry. They are utilised in a variety of sectors. For example, we employ electroplating, which is based on displacement reaction, to keep iron items from rusting.

The displacement reaction is a kind of reaction in which a portion of one reactant is displaced by another reactant. It’s also known as a replacement reaction. As one ion of reactant is replaced by another ion of reactant. Thus, displacement reaction is defined as the elements which are more reactive metal displace less reactive element from its compound or solution.

Copper sulphate (CuSO4)  +  Zinc (Zn)  ⇢  Zinc sulphate (ZnSO4)  +  Copper (Cu)

In the above reaction blue color of copper sulphate is converted to colourless of zinc sulphate.

Displacement order: A metal that is located above other metal has a tendency to displace less reactive metal (a metal which is below) in the reactivity series. A displacement reaction occurs when a highly reactive metal ( that forms positive ions more easily) displaces a less reactive metal from a compound or salt.

Types of Displacement Reactions

There are two types of displacement reactions, that are:

Single Displacement Reaction

Single displacement reactions is defined as the reaction in which one (highly reactive) element replaces another element from its compound or salt are called single displacement reactions. generally, they are shown as:-

X + Y-Z ⇢ X-Z + Y

In the general reaction, X is more reactive than Y. Generally, metals and their salts give this type of reaction. In these reactions metals that are more reactive can displace less reactive metal from its salt. For example, potassium (K) is more reactive than magnesium (Mg), so potassium replaces magnesium from magnesium chloride (MgCl2). These reactions are as follows:

2K + MgCl ⇢ 2KCl + Mg 

Some of the examples of single displacement reaction are as follows:

  • Reaction between zinc (Zn) and copper sulphate (CuSO4) is as,

Zn + CuSO4  ⇢  ZnSO4 + Cu

  • Reaction between copper(Cu) and silver nitrate (AgNO3) is as,

Cu + 2AgNO3  ⇢  CuNO3 + 2Ag

  • Reaction between lead (Pb) and copper chloride (CuCl2) is as,

Pb + CuCl2  ⇢  PbCl2 + Cu

  • Reaction between iron (Fe) and copper sulphate (CuSO4) is as,

Fe + CuSO4  ⇢  FeSO4 + Cu

Double Displacement Reaction

Double displacement reactions occur mostly in aqueous solutions, where ions precipitate and exchange ions. Double displacement reactions are those reactions in which the cations and anions of reactants replace each other. Generally, they are shown as,

AB + XY  ⇢ XB + AY

Double Displacement reaction

Some of the examples of double displacement reaction are as follows:

  • Reaction between sodium chloride (NaCl) and silver nitrate(AgNO3) is as,

AgNO3 + NaCl  ⇢   AgCl + NaNO3 

  • Reaction between potassium nitrate (KNO3) and aluminum chloride (AlCl3),

KNO3 + AlCl3  ⇢   Al(NO3)3 + KCl

  • Reaction between lead nitrate (Pb(NO3)2) and potassium iodide (KI),

Pb(NO3)2 + 2KI  ⇢  2KNO3 + PbI2

  • Reaction between iron chloride (FeCl3) and barium hydroxide (Ba(OH)2),

FeCl3 + Ba(OH) ⇢  Fe(OH)3 + BaCl2  

  • Reaction between barium chloride (BaCl2) and copper sulphate (CuSO4),

BaCl2 + CuSO4 ⇢  BaSO4 + CuCl2

Reactivity Series

The reactivity series is a grouping of metals based on their reactivity, from most reactive to least reactive. As a result, a metal reactivity series may be described as a group of metals arranged in decreasing order of reactivity. It is sometimes referred to as an activity series. Metals’ reactivity is caused by either their incomplete outer orbitals or their electrical structure. Metals lose electrons, resulting in the formation of positively charged ions. Metals with higher atomic numbers are more reactive because their electrons are farther away from the positively charged nucleus. As a result, they may be readily removed.

The reactivity is shown below in which the upper element in the table displaces the lower element from their solution or compound.

Symbol

 Element                  

K

Potassium (Highly reactive metal)    

Ba

Barium

Ca

Calcium

Na

Sodium

Mg

Magnesium

Al

Aluminium

Zn

Zinc

Fe

Iron

Ni

Nickel

Sn

Tin

Pb

lead

H

Hydrogen

Cu 

Copper

Hg

Mercury

Ag

Silver

Au

Gold

Pt

Platinum

Metals ranging from potassium to calcium are extremely reactive and can even react with water. Metals ranging from magnesium to lead can react with acids. Metals ranging from copper to platinum are extremely inert and do not react with any other material under normal conditions. This is why platinum and gold do not corrode easily and do not produce oxides. While metals such as zinc, aluminium, magnesium, calcium, and others readily produce oxides. Although hydrogen is a nonmetal, it has been included in the reactivity series because it aids in the comparison of metal reactivity.

Some of the Important Features of the Reactivity series

  • The reducing tendency of metals at the top of the table has high, that is why they are easily oxidized. These metals can get tarnished or corrode very easily.
  • The electro-positivity (tendency to lose electrons) of the elements get reduced while moving down the reactivity series of metals.
  • The tendency to reduce the metals becomes weaker while traversing down the series.
  • On reaction with dilute HCl or dilute H2SO4, all metals that are found above hydrogen in the activity series liberate H2 gas up.
  • Higher ranking metals require greater amounts of energy for their isolation from ores and other compounds.

Applications of Reactivity Series

The reactivity series provides the study of properties and reactivities of the metals, Apart from these reactivity series also provide several other important applications. For example, the result we get out of the reactions between metals and acids, metals and water, and single displacement reactions between metals can be predicted.

  • Reaction Between Metals and Water: Calcium and the metals that are more reactive than calcium in the reactivity series can react with cold water to form the corresponding hydroxide while liberating hydrogen gas. For example, the reaction between potassium and water yields potassium hydroxide and H2 gas, as described by the chemical equation provided below.

2K + 2H2O → 2KOH + H2

Reaction with Acid and bases: Metals, displace hydrogen from its dilute acids which are more reactive than hydrogen and form respective metal salts and hydrogen gas.

Metal + dilute acid → Salt + Hydrogen gas

Sodium metal has a tendency to displace hydrogen from hydrogen chloride (HCl) to form sodium chloride and liberate hydrogen gas. the reaction is given below:

2Na(s) + 2HCl (dilute)  →  2NaCl (aq)  +  H2(g)

Sample Questions

Question 1: Mention Physical properties of metals.

Answer:

Some of the physical properties of metals are:

  • Good conductor of heat and electricity.
  • Malleable
  • Ductile
  • Sonorous
  • Lustrous
  • Hard, high melting and boiling point.

Question 2: Aluminium foils is used in wrapping of food items , why?

Answer:

Due to property of its malleability it can be converted into thin sheets, than other metals it is cheaper and aluminium do not react with food items for long time, that’s why aluminium foils is used in wrapping foods.

Question 3: Name two metals which reacts vigorously air and water, where they were kept?

Answer:

Sodium and Potassium reacts vigorously with air and water. therefore they are kept in kereosene.

Question 4: Which metal float in water and why ?

Answer:

Calcium floats in water because hydrogen gas formed on adding calcium to water, then water sticks to the surface of calcium and make it float in water.

Question 5: Write a reaction that involves the reaction of sodium with water.

Answer:

Reaction of Sodium and water is explosive and it takes place as:

2Na (Sodium)  +  2H2O (water)  ⇢  2Na(OH) (Sodium hydroxide)  +  H2⇡ (Hydrogen gas)


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