19+ Double Decomposition Reaction Example: Detailed Explanations


Double decomposition reaction is the reaction in which the exchange of ions within two molecules or compounds takes place to form a new compound or molecule.

Double decomposition reaction is generally occurs between ionic molecules. The final product of double decomposition reaction is the formation of precipitates. The bonds formed between the atoms or elements of the molecule are either covalent or ionic in nature. In this editorial we are discussing about the various double decomposition reaction examples with detailed explanations.

The double decomposition reaction can be in the following form:

double decomposition reaction example
General double decomposition reaction

In double decomposition reaction acids and bases can also precipitates.The product of double decomposition reaction will have the same bonds in it as the bonds having in the reactants of the molecules. Generally water is the solvent for this kind of reactions i.e. double decomposition reactions.

The double decomposition reaction is referred by various names as double displacement reaction, exchange decomposition reaction, salt metathesis reaction and double replacement reactions. But the term double decomposition reaction is referred if one or more of the reactant molecule does not soluble in the solvent.

The simplest method for the identification of double displacement reaction is to identify the exchange of cations with anions i.e. we have to check that whether the cations get exchanged by anions and anions get exchanged by cations. Another point to identify is the state of matter of reactant and product i.e. to check whether the reactants are aqueous or not and the product formed should be in solid state. As generally the product formed is precipitate so it should be in solid form only.

Double decomposition reaction can be classified into various types like neutralization reaction, alkylation reaction, counter ion exchange reaction, acid carbonate reaction, aqueous metathesis reaction with double decomposition (double decomposition reaction) and aqueous metathesis reaction with precipitation (precipitation reaction).

In chemistry field there are two types are double decomposition reactions are generally used i.e. 1) neutralization reaction and 2) precipitation reaction.

In first type neutralization reaction, the double decomposition reaction occurs between acids and bases. The neutralization reaction generally produces a salt which is an ionic compound if the solvent used as water. These kind of reactions is done always in forward path i.e. it is a forward reaction if the reactants involves at least either a strong acid or a strong base.

The general example of neutralization reaction is the reaction between baking soda and vinegar shows in the volcano in school or college science exhibitions. In this reaction when the baking soda and vinegar reacts with each other which then exerts a carbon dioxide gas due to which the fizz occurs looks like a volcano.

The preliminary neutralization reaction is as follows:

NaHCO3 + CH3COOH (aq) → H2CO3 + NaCH3COO

In the above reaction sodium bicarbonate (sodium hydrogen carbonate) commonly known as baking powder or soda, is reacted with acetic acid (vinegar) which produced carbonic acid and sodium acetate.

In second type precipitation reaction which occurs within two ionic molecules in aqueous condition to produce a novel ionic insoluble molecule.

The example of precipitation reaction is the reaction within potassium iodide (KI) and lead nitrate [Pb(NO3)2]  to produce a soluble potassium nitrate and an insoluble lead iodide.

Pb(NO3)2 (aq) + 2 KI (aq) → 2 KNO3 (aq) + PbI2 (s)

The lead iodide is produced in the form of precipitate, rather the water which is used as a solvent and the soluble products and reactants are referred as supernatant or supernate. As the product comes out of the solution, the reaction goes into forward path and due to these there is a formation of precipitates occurs.

Here we can see that the cations get exchanged with the anions, but the compounds are written in the way is quite tricky to identify the anions exchange. The way to find the reaction as a double decomposition reaction is to see the anions atoms and compare them on reactions both sides.  

Here are the more double decomposition reaction examples are as follows:

AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3 (aq)

In this reaction sodium chloride is reacted with silver nitrate gives the formation of silver chloride and sodium nitrate.

H2SO4 + BaCl2 → 2HCl + BaSO4

Here in above reaction sulphuric acid is reacted with barium chloride gives the production of hydrochloric acid and barium sulphate.

Na2SO4 (aq) + BaCl2 → BaSO4 (s) + 2NaCl (aq)

In above reaction sodium sulphate gets reacted with barium chloride gives the formation of barium sulphate and sodium chloride.

NaOH (aq) + HCl (aq) → NaCl (aq) + H2O (l)

In this reaction when sodium hydroxide is reacted with hydrochloric acid gives the formation of sodium chloride and water.

2AgNO3 + K2CrO4 → 2KNO3 + Ag2CrO4

In the above reaction, silver nitrate is reacted with potassium chromate which gives the formation of potassium nitrate and silver chromate.

2NaCN + H2SO4 → Na2SO4 + 2HCN

In this above reaction, sodium cyanide is reacted with sulphuric acid which gives the formation of sodium sulphate and hydrogen cyanide.

Ca(OH)2 + 2HCl → CaCl2 + 2H2O

In the above reaction when calcium hydroxide is reacted with hydrochloric acid which gives the formation of calcium chloride and water.

NaOH + NH4Cl → NaCl + NH4OH

In the above reaction, sodium hydroxide is reacted with ammonium chloride which gives the formation of sodium chloride and ammonium hydroxide.

CaCl2 + (NH4)2CO3 → CaCO3 + NH4Cl

In the above reaction we can see, the calcium chloride is reacted with ammonium carbonate which gives the formation of sodium carbonate and ammonium chloride.

Ca(OH)2 + 2 NH4Cl → CaCl2 + 2 NH4OH

In the above reaction when calcium hydroxide is reacted with ammonium chloride gives the production of calcium chloride and ammonium hydroxide.

CuSO4 + H2S → CuS + H2SO4

In the above reaction when copper (ii) sulphate is reacted with hydrogen sulphide gas gives the production of copper sulphide and sulphuric acid.

AgNO3 + KCl → AgCl + KNO3

In the above reaction when silver nitrate is reacted with potassium chloride gives the formation of silver chloride and potassium nitrate.

Na2CO3 (aq) + BaBr2 (aq) → 2 NaBr (aq) + BaCO3 (s)

In the above mentioned reaction, when sodium carbonate is reacted with barium bromide gives the formation of sodium bromide and barium carbonate.

Al2(SO4)3(aq)  +  3 BaCl2(aq)   →   3 BaSO4(s)   +   2 AlCl3(aq)

In the above reaction when aluminium sulphate is reacted with barium chloride gives the formation of barium sulphate and aluminium chloride.

MgSO4 (aq) + 2 NaOH (aq) →    Na2SO4 (aq) +    Mg(OH)2 (s)

In the above reaction when magnesium sulphate is reacted with sodium hydroxide gives the production of sodium sulphate and magnesium hydroxide.

CaBr2 (aq) +   2 AgNO3 (aq) →   2 AgBr (s) +   Ca(NO3)2 (aq)

In the above reaction calcium bromide is reacted with silver nitrate which gives the production of silver bromide and calcium nitrate.

K2S (aq) + Pb(NO3)2 (aq) →  PbS (s) +   2 KNO3 (aq)

In the above reaction when potassium sulphide is reacted with lead nitrate gives the formation of lead sulphide and potassium nitrate.

3Ca(NO3)2(aq) +  2K3PO4(aq)  → Ca3(PO4)2(s)  + 6KNO3(aq)

In the above reaction when calcium nitrate is reacted with tripotassium phosphate which gives the formation of tricalcium phosphate and potassium nitrate.

Dr. Shruti Ramteke

Hello everyone I am Dr. Shruti M Ramteke, i did my Ph.D in chemistry. I have five years of teaching experience for 11-12 standard, B,Sc and MSc in chemistry subject. I have published total five research articles during Ph.D on my research work and i have fellowship from UGC for my Ph.D. My Masters with specilization Inorganic chemistry and my graduation with chemistry, zoology and environmental science subjects. thank You

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