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NCERT Solutions for Chapter 1 Chemical Reactions and Equations is the article that provides all the solutions from the NCERT textbook with the intent to help students in their academic journey. All the problems in the NCERT book's exercise at the end of the chapter are discussed in detail here which helps students clear their doubts regarding the solution of the problems.
The topics covered in the 'Chemical Reactions and Equations' chapter in Class 10 Chemistry are:
Solution:
As Lead (Pb) is losing oxygen, it undergoes reduction, whereas carbon is gaining oxygen to form carbon dioxide. Thus lead oxide is getting reduced and carbon is getting oxidised.
Option (ii) is the correct answer.
Solution:
In this reaction, aluminium (Al) being a more reactive metal than Fe, displaces iron (Fe) from iron oxide (Fe2O3) and reacts with oxygen to form aluminium oxide (Al2O3). As only one metal is being displaced here, it is a displacement reaction.
Thus option (d) is the correct answer.
Solution:
When dilute Hydrochloric acid (HCl) is added to iron fillings (Fe), following reaction takes place:
Fe + HCl (dil.) → FeCl2 + H2 (g)
Thus it leads to formation of ferrous chloride and hydrogen gas.
Thus option (a) is the correct answer.
Solution:
An equation in which all the elements in the compounds on both sides of the chemical equation i.e. reactants and products are equal is called a balanced equation. Chemical equation should be balanced to uphold the law of conservation of mass during a chemical reaction.
Solution:
The balanced chemical equations for the given reactions are as follows:
a) 3H2 + N2 → 2NH3
b) 2H2S + 3O2 → 2H2O + 2SO2
c) 3BaCl2 + Al2(SO4)3 → 2AlCl3 + 3BaSO4
d) 2K + 2H2O → 2KOH + H2
Solution:
The balanced chemical equations for the given reactions are as follows:
(a) 2HNO3 + Ca(OH)2 → Ca(NO3)2 + 2H2O
(b) 2NaOH + H2SO4 → Na2SO4 + 2H2O
(c) NaCl + AgNO3 → AgCl + NaNO3
(d) BaCl2 + H2SO4 → BaSO4 + 2HCl
Solution:
The balanced chemical equations for the given reactions are as follows:
(a) 2Ca(OH)2 + 2CO2 → 2CaCO3 + 2H2O
(b)Zn + 2AgNO3 → Zn(NO3)2 + 2Ag
(c) 2Al + 3CuCl2 → 2AlCl3 + 3Cu
(d) BaCl2 + K2SO4 → BaSO4 + 2KCl
Solution:
The balanced chemical equations along with the type of reaction for the given reactions are as follows:
a) 2KBr + BaI2 → 2KI + BaBr2 (It is a double displacement reaction)
b) ZnCO3 → ZnO + CO2 (It is a decomposition reaction)
c) H2 + Cl → 2HCl (It is a combination reaction)
d) Mg + 2HCl → MgCl2 + H2 (It is a displacement reaction)
Solution:
The reaction in which heat or energy is released in the surroundings is called exothermic reaction. For example, burning of wood, reaction of HCl and water, etc. The reaction in which heat or energy is absorbed from the surroundings is called endothermic reaction. For example, melting of ice, evaporation of liquid, etc.
Solution:
During respiration, the food broken down to glucose during digestion reacts with oxygen to form carbon dioxide, water and energy. Thus energy is released during respiration. Hence respiration is an exothermic reaction.
C6H12O6 → CO2 + H2O + Δ(Energy)
Solution:
In a combination reaction, two or more reactants combine to form a product whereas in a decomposition reaction, a reactant breaks into two or more products. Thus decomposition reaction is the opposite of combination reaction. Some equations for decomposition reactions are:
- C6H12O6 → CO2 + H2O + Δ(Energy)
- ZnCO3 → ZnO + CO2
Solution:
The required chemical equations are as follows:
- When energy is supplied in the form of heat, it is called thermal decomposition reaction
2KClO3 + Δ → 2KCl + 3O2
- When energy is supplied in the form of electricity, it is called thermal electrolytic decomposition reaction
NaCl → Na + Cl2
- When energy is supplied in the form of light, it is called photodecomposition reaction
H2O2 → H2 + O2
Solution:
The difference between displacement and double displacement reaction is as follows:
Displacement Reaction | Double Displacement Reaction |
|---|---|
In this reaction, a more reactive element displaces a less reactive element from its compound. | In this reaction, two elements displace each other from their compounds and form new compounds. |
In it, the displacement of one element takes place. | In it, both the elements perform a mutual exchange of ions to form new products. |
Example: | Example: |
Solution:
The reaction involved in this process is:
AgNO3 (silver nitrate) + Cu (copper) → CuNO3 (copper nitrate) + Ag (silver)
Solution:
Sometimes in a reaction, the product formed is in solid state and settles at the bottom of the container. It is called precipitate and the reaction is thus termed as precipitation reaction. For example, the reaction of sodium hydroxide and magnesium chloride forms a white precipitate of magnesium hydroxide.
NaOH + MgCl2 → NaCl + Mg(OH)2
Solution:
(a) Oxidation: When oxygen is added to a compound or element, it is called oxidation reaction.
H2 + O2 → H2O
Na + O2 → Na2O
(b) Reduction: When oxygen is removed from a compound, it is called reduction reaction.
H2O2 → H2 + O2
CuO + H2 → Cu + H2O
Solution:
The element X is copper (Cu). When copper is heated in air, it forms copper oxide by oxidation which is black in color. Thus the black colored compound formed is copper oxide.
Solution:
Iron reacts with atmospheric oxygen and moisture and undergoes corrosion to form rust. Painting prevents the surface of iron to come in contact with oxygen and moisture and thus prevents rusting or corrosion of the iron metal.
Solution:
Oil and fat present in food undergoes oxidation reaction by reacting with oxygen which leads to an unpleasant taste and odour in the food called rancidification. Flushing nitrogen in the food items prevents the reaction of oil and fat with oxygen and maintains the quality of the food and prevents rancidity.
Solution:
(a) Corrosion: It is a process by which the metals undergo reaction with atmospheric oxides and other compounds in the atmosphere to form their oxides and other compounds which cause degradation of the metal. For example, rusting of iron, copper vessels turning green
(b) Rancidity: The condition when the food containing oil and fat reacts with atmospheric oxygen to produce an unpleasant taste and odor is called rancidity. It renders the food unfit for consumption.
