What is a Reaction Experiment?
Matter undergoes three different types of changes: physical changes, chemical changes, and nuclear changes. From these changes, the composition of a substance is not altered by physical changes, such as freezing and evaporation. Chemical changes, or in reactions, the formation of new substances are formed. These substances are formed when bonds are formed or broken.
Types of Chemical Reactions Experiment
The types of chemical reaction experiment depend upon the reactivity of the chemicals. The types of reaction experiments are:
Combination reaction (Synthesis reaction experiment)
Decomposition reaction
Single displacement reaction experiment (Single replacement reaction)
Combustion reaction
Combination Reaction-
In this reaction, two or more two molecules react (combine) and form a single new compound. This type of reaction experiment is also called a synthesis reaction experiment. One combination reaction represents the combination of two or more elements or molecules for the purpose of product formation. Synthesis reaction experiment can be represented as:
A + B → AB
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Example: Formation of sodium chloride salt (NaCl)
2 Na (s) + Cl2 (g) → 2NaCl (s)
Reaction of elements with oxygen. Metal and non-metals react readily with the free oxygen and form oxides.
2 Mg (S) + O2 (g) → 2MgO (s)
Decomposition Reaction-
In this type of reaction, complex compounds break into simpler ones. For this reaction, a source of energy is required to break the existing bonds of the complex compound. Decomposition reaction represents the breaking down of the complex compound bond for the formation of simpler compounds. This type of reaction can be represented as
AB → A + B
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This type of reaction occurs in the presence of light, heat, or electricity. When the binary compound is decomposed to form a product, it is called a simple decomposition reaction.
2 HgO (s) → 2 Hg (l) + O2 (g)
In the decomposition reaction, the reactant can get converted into either elemental form or compound form. In the decomposition of calcium carbonate (CaCO3), calcium oxide and carbon dioxide molecule is formed as a product. Bases or alkalis get decomposed on heating.
2 NaOH (s) + Na2O (s) + H2O (g)
Single Displacement Reaction Experiment-
In this type of reaction one element of the reactant replaces the similar type of element of the different reactant compound. This type of reaction is also known as a single replacement reaction experiment. This type of reaction depends upon the reactivity of the elements. Highly reactive elements replace low reactive elements. Single displacement reaction experiment can be represented as:
A + BC → AC + B
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Example: Mg (s) + Cu(NO3)2 (aq) → Mg(NO3)2 (aq) + Cu (s)
The above reaction represents that magnesium is more reactive than copper. Therefore, magnesium replaces copper.
Combustion Reaction-
Combustion reaction is a type of reaction in which reactants react with oxygen and release energy or heat in the surrounding. A combustion reaction takes place in the presence of oxygen. This type of reaction can be of two types:
Incomplete combustion
Complete combustion
Organic compounds when undergoes complete combustion produces carbon dioxide, water molecules in the gaseous state, and energy.
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C3H8 (g) +5 O2 (g) → 3 CO2 (g) + 4 H2O (g)
Generally, hydrocarbons are used in combustion reactions for energy production. A combustion reaction is an exothermic reaction.
Double Displacement Reaction-
In these types of chemical reactions experiment the positive ions (cation) and negative ions (anion) exchange their position to form new compounds. Double displacement reactions generally occur in an ionic compound. Double displacement reaction is represented as:
AB + CD → AD + CB
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In the above reaction, AB and CD are ionic compounds. In AB A is a cation and B is an anion. In CD C is a cation and D is an anion.
Comparison of Single Replacement Reaction Experiment and Double Displacement Reaction
In a single replacement reaction experiment, only one element replaces the other in the two reactants, depending upon the reactivity. While in a double displacement reaction reactants exchange the cation or anion of the two ionic compounds. In a single replacement reaction experiment, both elemental state and ionic state can participate. While in a double displacement reaction only ionic compounds can participate.
Did You Know?
You may think that chemical reaction occurs only in the laboratories, but it also occurs in the human body, plants, and the environment.
All types of chemical reactions do not occur at the same rate. Some reaction completes in a few minutes and some get completed in years.
The rate of a chemical reaction can be altered by the addition of a catalyst.
In physical changes, no chemical reaction occurs.
When a single reaction completes in the series of the reaction, it is termed a chain reaction.
FAQs on Types of Reactions Experiment
1. What are the five main types of chemical reaction experiments studied in the CBSE syllabus?
Based on the CBSE curriculum for the 2025-26 session, the five primary types of chemical reactions you will perform and observe in experiments are:
- Combination Reaction: Where two or more substances combine to form a single new substance.
- Decomposition Reaction: Where a single compound breaks down into two or more simpler substances.
- Single Displacement Reaction: Where a more reactive element displaces a less reactive element from its compound.
- Double Displacement Reaction: Where two compounds react by exchanging their ions to form two new compounds.
- Combustion Reaction: A reaction where a substance rapidly reacts with an oxidant, usually oxygen, to produce heat and light.
2. How can one visually identify a combination reaction in an experiment?
In a typical school laboratory experiment, you can identify a combination reaction by observing two or more reactants forming a single product. A classic example is heating magnesium ribbon in the air. The magnesium (a solid) reacts with oxygen (a gas) to form magnesium oxide, a single white powdery substance. The formation of just one product from multiple reactants is the key indicator.
3. What is the key difference between single displacement and double displacement reactions?
The primary difference lies in what is being exchanged. In a single displacement reaction, a more reactive element displaces another element in a compound (A + BC → AC + B). In a double displacement reaction, two ionic compounds exchange their respective cations and anions to form two entirely new compounds (AB + CD → AD + CB). Essentially, it's one element being swapped versus a mutual exchange of ions.
4. Why is energy, such as heat or light, often required for a decomposition reaction to occur?
Energy is required for a decomposition reaction because these reactions involve breaking the existing chemical bonds within a complex compound. Chemical bonds store energy, and to break them, an external energy input is necessary. This energy overcomes the forces holding the atoms together, allowing the compound to break down into simpler substances. For example, thermal decomposition uses heat, while photolysis uses light energy to break the bonds.
5. What is the role of the reactivity series in predicting a single displacement reaction?
The reactivity series is crucial because it acts as a guide to predict whether a single displacement reaction will happen. It ranks metals in order of their reactivity. For a displacement to occur, the element that is on its own must be more reactive (higher up in the series) than the element it is trying to displace from the compound. For example, zinc (Zn) can displace copper (Cu) from copper sulphate solution because zinc is more reactive than copper.
6. What determines if the combustion of a hydrocarbon is complete or incomplete?
The determining factor for a combustion reaction is the availability of oxygen.
- Complete combustion occurs when there is a sufficient or excess supply of oxygen. It produces carbon dioxide (CO₂) and water (H₂O).
- Incomplete combustion happens when the oxygen supply is limited. It produces carbon monoxide (CO), a toxic gas, and/or soot (solid carbon), along with water.
7. Can a chemical reaction be classified as both a combination and a combustion reaction? Explain with an example.
Yes, a reaction can fit into both categories. For example, the burning of magnesium in oxygen (2Mg + O₂ → 2MgO) is a combination reaction because two substances (Mg and O₂) combine to form a single product (MgO). It is also a combustion reaction because magnesium is reacting with oxygen and releasing a significant amount of energy in the form of intense light and heat.
8. How is a precipitation reaction an example of a double displacement reaction?
A precipitation reaction is a specific type of double displacement reaction where one of the new compounds formed is an insoluble solid, called a precipitate. When two aqueous solutions of ionic compounds are mixed, they exchange ions. If the newly formed cation-anion pairing results in a compound that does not dissolve in water, it settles out of the solution as a solid. For instance, mixing silver nitrate (AgNO₃) and sodium chloride (NaCl) solutions results in the formation of a white precipitate of silver chloride (AgCl).
