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CBSE course 10 science Notes chapter 1 chemical Reactions and also Equations

Chemical Reactions and Equations: Balanced and also unbalanced chemistry equations and balancing of chemistry equations.

What is a chemistry reaction class 10?

Chemical Reaction: The transformation of chemistry substance into another chemical problem is known as chemistry Reaction. For example: Rusting the iron, the setup of milk right into curd, digestion of food, respiration, etc.

In a chemistry reaction, a brand-new substance is created which is completely different in nature from the original substance, so in a chemistry reaction, a chemical change takes place.Only a rearrangement of atoms takes ar in a chemical reaction.

The substances i m sorry take component in a chemical reaction are referred to as reactants.The brand-new substances produced as a result of a chemistry reaction are referred to as products.

Example: The burning of magnesium in the wait to kind magnesium oxide is an instance of a chemistry reaction.2Mg(s) + O2(g) (underrightarrow riangle ) 2MgO(s)Before burning in air, the magnesium ribbon is cleaned by rubbing v sandpaper.This is excellent to eliminate the protective layer of an easy magnesium lead carbonate from the surface of the magnesium ribbon.

Reactant: Substances i m sorry take part in a chemical reaction are called reactants.Example: Mg and also O2.

Product: brand-new substance created after a chemistry reaction is referred to as a product.Example: MgO.

Characteristics of chemistry Reactions :(i) development of gas: The chemistry reaction between zinc and dilute sulphuric mountain is characterised by the development of hydrogen gas.Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) ↑

(ii) adjust in Colour: The chemistry reaction between citric acid and also purple coloured potassium permanganate systems is characterised by a change in colour from purple to colourless.The chemistry reaction in between sulphur dioxide gas and acidified potassium dichromate systems is defined by a adjust in colour from orange to green.

(iii) change in state that substance: The combustion reaction that candle wax is characterised by a change in state indigenous solid to liquid and gas (because the wax is a solid, water formed by the combustion of wax is a fluid at room temperature whereas, carbon dioxide produced by the combustion of wax is a gas). There are some chemical reactions which deserve to show more than one characteristics.

(iv) readjust in temperature: The chemistry reaction between quick lime water to type slaked lime is characterized by a change in temperature (which is a climb in temperature).The chemical reaction in between zinc granules and also dilute sulphuric mountain is additionally characterised by a adjust in temperature (which is a rise in temperature).

(v) development of precipitate: The chemical reaction between sulphuric acid and barium chloride systems is characterised by the formation of a white precipitate of barium sulphate.BaCl2(aq) + H2SO4(aq) → BaSO4(s) (ppt) + 2HCl(aq)

What is a chemistry Equation class 10?

Chemical Equation: representation of chemistry reaction utilizing symbols and formulae of the building material is called Chemical Equation.Example: A + B → C + DIn this equation, A and also B are dubbed reactants and C and also D are called the products. The arrowhead shows the direction of the chemistry reaction. Condition, if any, is written generally above the arrow.

When hydrogen reacts through oxygen, it gives water. This reaction deserve to be represented by the adhering to chemical equation:Hydrogen + Oxygen → WaterH2 + O2 → H2OIn the first equation, words room used and in second, symbols of building material are used to compose the chemistry equation. For convenience, the symbol of substance is supplied to represent chemical equations.A chemical equation is a means to stand for the chemical reaction in a concise and informative way.A chemistry equation can be separated into 2 types: balanced Chemical Equation and Unbalanced chemical Equation.

(a) well balanced Chemical Equation: A balanced chemical equation has the number of atoms of each facet equal on both sides.Example: Zn + H2SO4 → ZnSO4 + H2In this equation, number of zinc, hydrogen and sulphate space equal on both sides, so the is a well balanced Chemical Equation.According to the regulation of conservation of Mass, mass have the right to neither be developed nor ruined in a chemical reaction. To obey this law, the full mass of elements present in reactants have to be same to the full mass of elements present in products.

(b) Unbalanced chemical Equation: If the number of atoms of each facet in reaction is no equal to the number of atoms of each element present in the product, then the chemistry equation is called Unbalanced chemical Equation.Example: Fe + H2O → Fe3O4 + H2In this example, a variety of atoms of elements are not equal on two sides that the reaction. For example; on the left-hand side just one stole atom is present, while three iron atom are present on the right-hand side. Therefore, that is an unbalanced chemistry equation.

Balancing a chemistry Equation: come balance the given or any chemical equation, follow this steps:Fe + H2O → Fe3O4 + H2Write the number of atoms of aspects present in reactants and also in products in a table as presented here.

Name the atomNo. Of atoms in the reactantNo. Of atom in the product

Balance the atom which is maximum in number ~ above either side of a chemistry equation.In this equation, the number of oxygen atom is the maximum on the RHS.To balance the oxygen, one requirements to main point the oxygen ~ above the LHS through 4, so that, the number of oxygen atoms becomes equal on both sides.Fe + 4 × H2O → Fe3O4 + H2Now, the number of hydrogen atom becomes 8 ~ above the LHS, which is an ext than that on the RHS. Come balance it, one demands to main point the hydrogen top top the RHS by 4.Fe + 4 × H2O → Fe3O4 + 4 × H2After that, the variety of oxygen and also hydrogen atom becomes same on both sides. The number of iron is one on the LHS, while the is 3 on the RHS. Come balance it, multiply the steel on the LHS by 3.3 × Fe + 4 × H2O → Fe3O4 + 4 × H2Now the number of atoms that each element becomes equal on both sides. Thus, this equation becomes a well balanced equation.

Name that atomNo. Of atom in the reactantNo. Of atoms in the product

After balancing, the over equation can be composed as follows:3Fe + 4H2O → Fe3O4 + 4H2.

To make Equations more Informative:Writing the signs of physical says of building material in a chemical equation:By writing the physical says of substances, a chemistry equation becomes much more informative.

Gaseous state is stood for by price (g).Liquid state is stood for by price (l).Solid state is created by prize (s).Aqueous equipment is written by symbol (aq).Writing the problem in which reaction take away place: The problem is usually written over and/or listed below the arrowhead of a chemistry equation.

Thus, by creating the signs of the physics state of substances and also condition under i m sorry reaction takes place, a chemistry equation can be made more informative.

What are the varieties of a chemistry reaction class 10?

Types of chemistry Reactions: combination Reaction, Decomposition Reaction, Displacement Reaction, dual Displacement Reaction, Neutralization Reactions, Exothermic – Endothermic Reactions and also Oxidation-Reduction Reactions.

Types of chemistry Reactions:Chemical reactions have the right to be share in complying with types:(i) combination Reaction: reaction in which 2 or more reactants combine to form one product space called combination Reactions.A general combination reaction have the right to be represented by the chemical equation provided here:A + B → ABExamples:When magnesium is burned in the wait (oxygen), magnesium oxide is formed. In this reaction, magnesium is combined with oxygen.Mg(s) + O2(g) → 2MgO(s)Magnesium + Oxygen → Magnesium Oxide

When carbon is burned in oxygen (air), carbon dioxide is formed. In this reaction, carbon is combined with oxygen.C (s) + O2(g) → CO2(g)Carbon + Oxygen → Carbon dioxide

(ii) Decomposition Reaction: reaction in i beg your pardon one link decomposes in 2 or much more compounds or facets are known as Decomposition Reaction. A decomposition reaction is just the the contrary of combination reaction.A general decomposition reaction have the right to be represented as follows :AB → A + BExamples:When calcium lead carbonate is heated, that decomposes right into calcium oxide and carbon dioxide.CaCO3(s) (underrightarrow warmth ) CaO(s) + CO2(g)Calcium lead carbonate → Calcium oxide + Carbon dioxide

When ferric hydroxide is heated, the decomposes into ferric oxide and water2Fe(OH)3(s) (underrightarrow riangle ) Fe2O3(s) + 3H2O(l)

Thermal Decomposition: The decomposition that a problem on heating is recognized as thermal Decomposition.Example: 2Pb(NO3)2(s) (underrightarrow warmth ) 2PbO(s) + 4NO2(g) + O2(g)

Electrolytic Decomposition: reaction in i m sorry compounds decompose into less complicated compounds due to the fact that of pass of electricity, are well-known as Electrolytic Decomposition. This is likewise known as Electrolysis.Example: When electricity is pass in water, the decomposes into hydrogen and oxygen.2H2O(l) (xrightarrow < Electrolysis > Electricquad present ) 2H2(g) + O2(g)

Photolysis or picture Decomposition Reaction: reaction in i beg your pardon a compound decomposes since of sunshine are known as Photolysis or picture Decomposition Reaction.Example: once silver chloride is put in sunlight, that decomposes right into silver metal and also chlorine gas.2AgCl(s) (white) (underrightarrow sunshine ) 2Ag(s) (grey) + Cl2(g)

Photographic paper has a coat of silver chloride, which turns right into grey once exposed to sunlight. The happens since silver chloride is colourless while silver- is a grey metal.

(iii) Displacement Reaction: The chemistry reactions in i m sorry a more reactive facet displaces a much less reactive element from a link is recognized as Displacement Reactions. Displacement reactions are likewise known as Substitution Reaction or solitary Displacement/ instead of reactions.A basic displacement reaction deserve to be represented by utilizing a chemical equation as complies with :A + BC → AC + BDisplacement reaction takes location only as soon as ‘A’ is more reactive 보다 B. If ‘B’ is much more reactive than ‘A’, climate ‘A’ will certainly not displace ‘C’ from ‘BC’ and also reaction will not be acquisition place.Examples:When zinc reacts through hydrochloric acid, it provides hydrogen gas and also zinc chloride.Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)

When zinc reacts with copper sulphate, it creates zinc sulphate and also copper metal.Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)

(iv) twin Displacement Reaction: reaction in i m sorry ions are exchanged between two reaction forming brand-new compounds are called double Displacement Reactions.AB + CD → AC + BDExamples:When the solution of barium chloride reacts through the equipment of salt sulphate, white precipitate that barium sulphate is formed in addition to sodium chloride.BaCl2(aq) + Na2SO4(aq) → BaSO4(s) (Precipitate) + 2NaCl(aq)

When salt hydroxide (a base) reacts v hydrochloric acid, salt chloride and water are formed.NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)

Note: dual Displacement Reaction, in i m sorry precipitate is formed, is additionally known together precipitation reaction. Neutralisation reactions are additionally examples of dual displacement reaction.

Precipitation Reaction: The reaction in which precipitate is developed by the mix of the aqueous equipment of 2 salts is referred to as Precipitation Reaction.Example:


Neutralization Reaction: The reaction in i beg your pardon an mountain reacts v a base to kind salt and water by an exchange of ions is called Neutralization Reaction.Example:


(v) Oxidation and also Reduction Reactions:Oxidation: enhancement of oxygen or non-metallic aspect or remove of hydrogen or metallic facet from a link is recognized as Oxidation.Elements or link in which oxygen or non-metallic element is added or hydrogen or metallic aspect is gotten rid of are called to be Oxidized.Reduction: enhancement of hydrogen or metallic element or remove of oxygen or non-metallic facet from a link is referred to as Reduction.The compound or facet which go under reduction in referred to as to it is in Reduced.Oxidation and also Reduction take location together.Oxidizing agent:

The problem which gives oxygen for oxidation is called an Oxidizing agent.The problem which gets rid of hydrogen is also called an Oxidizing agent.

Reducing agent:

The substance which gives hydrogen because that reduction is referred to as a to reduce agent.The substance which clears oxygen is likewise called a to reduce agent.

The reaction in i m sorry oxidation and also reduction both take ar simultaneously is dubbed Redox reaction.When copper oxide is heated with hydrogen, climate copper metal and also hydrogen are formed.CuO + H2 → Cu + H2O(i) In this reaction, CuO is transforming into Cu. Oxygen is being gotten rid of from copper oxide. Removed of oxygen from a substance is referred to as Reduction, so copper oxide is being decreased to copper.

(ii) In this reaction, H2 is an altering to H2O. Oxygen is being added to hydrogen. Enhancement of oxygen come a substance is referred to as Oxidation, for this reason hydrogen is gift oxidised to water.

The problem which it s okay oxidised is the reducing agent.The problem which gets diminished is the oxidizing agent.

(vi) Exothermic and Endothermic Reactions:Exothermic Reaction: Reaction i beg your pardon produces power is called Exothermic Reaction. Most of the decomposition reactions are exothermic.Example:Respiration is a decomposition reaction in which power is released.

When quick lime (CaO) is added to water, that releases energy.

Endothermic Reaction: A chemical reaction in i m sorry heat energy is absorbed is called Endothermic Reaction.Example: Decomposition the calcium carbonate.


Effects the Oxidation reaction in day-to-day life: Corrosion and Rancidity.Corrosion: The procedure of slow conversion the metals right into their undesirable compounds due to their reaction through oxygen, water, acids, gases etc. Current in the atmosphere is called Corrosion.Example: Rusting of iron.

Rusting: Iron as soon as reacts through oxygen and moisture forms red substance which is called Rust.


The rusting of stole is a oxidation reaction.Corrosion (rusting) weakens the iron and also steel objects and also structures such together railings, car bodies, bridges and ships etc. And also cuts short their life.Methods to prevent Rusting

By painting.By greasing and oiling.By galvanisation.

Corrosion the Copper: Copper objects shed their lustre and shine after part time since the surface of this objects acquires a eco-friendly coating of basic copper carbonate, CuCO3.Cu(OH)2 as soon as exposed to air.


Corrosion of silver- Metal: The surface ar of silver steel gets tarnished (becomes dull) ~ above exposure come air, as result of the development of a coating of black silver sulphide(Ag2S) on its surface ar by the action of H2S gas present in the air.


Rancidity: The taste and odour the food products containing fat and oil alters when they room left exposed come air because that a long time. This is called Rancidity. The is caused as result of the oxidation the fat and oil current in food materials.

Methods to avoid rancidity:

By including anti-oxidant.Vacuum packing.Replacing wait by nitrogen.Refrigeration that foodstuff.

1. Chemical Reaction: throughout chemical reactions, the chemical composition that substances changes or new substances space formed.

2. Chemical Equation: chemistry reactions deserve to be created in chemical equation form which should constantly be balanced.

3. Types of chemistry Reactions:

Combination reaction: A single product is created from two or much more reactants.2Mg + O2 → 2MgO

Decomposition reaction: A solitary reactant breaks under to yield two or much more products.

Thermal decomposition: 2Pb(NO2)2 → 2PbO + 4NO2 + O2Electrolysis: 2H20 → 2H2 + O2Photochemical reaction: 2AgBr → 2Ag + Br2

Displacement reaction: One facet is displaced by an additional element.Zn + CuSO4 → ZnSO4 + Cu

Double displacement reaction: Exchange of ions in between reactants.AgNO3 + NaCl → AgCl + NaNO3

Redox reaction: Both oxidation and also reduction take ar simultaneously.CuO + H2 → Cu + H2O

Exothermic reaction: A chemical reaction in i beg your pardon heat energy is evolved.C + O2 → CO2 (g) + heat

Endothermic reaction: A chemistry reaction in i m sorry heat energy is absorbed.ZnCO3 + warmth → ZnO + CO2

Redox reaction: chemistry reaction in which both oxidation and also reduction take place simultaneously.

4. Oxidation: Reaction that involves the get of oxygen or loss of hydrogen.

5. Reduction: Reaction that shows the ns of oxygen or get of hydrogen.ZnO + C → Zn + COZnO is lessened to Zn—reduction. C is oxidized come CO—Oxidation.

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6. Effects that Oxidation reaction in Our everyday Life:

Corrosion: the is one undesirable adjust that occurs in steels when castle are attacked by moisture, air, acids and bases.Example, Corrosion (rusting) the Iron: Fe2O3. NH2O (Hydrated stole oxide)Rancidity: Undesirable readjust that takes ar in oil comprise food items as result of the oxidation of fat acids.Preventive techniques of rancidity: adding antioxidants come the food materials, storing food in the airtight container, flushing out air with nitrogen gas and also refrigeration.