Welcome to our comprehensive guide on mastering chemical equations and reactions for Class 10 students. In this article, we delve into the fascinating world of chemistry, specifically focusing on the essential topic of “chemical equations and reactions class 10.”
Chemical equations and reactions are fundamental concepts in chemistry that form the basis for understanding various chemical processes and transformations. As you progress through your Class 10 studies, this topic becomes increasingly important and lays the foundation for more advanced chemistry topics in higher grades.
In this guide, we will take you through the key aspects of chemical equations and reactions, including how to write and balance chemical equations, identifying different types of reactions, and understanding the underlying principles behind each reaction type.
By the end of this article, you will gain a thorough understanding of chemical equations and reactions, enabling you to confidently tackle related questions and problems in your Class 10 examinations and beyond. Let’s embark on this exciting journey into the world of chemical reactions and equations! For other chapter’s solution, visit NCERT Solutions Science Class 10 All Chapter
NCERT Chapter 1 Chemical Equations and Reactions Class 10 Solution
1. Why should a magnesium ribbon be cleaned before burning in the air?
Solution:
Before burning in air, it is crucial to clean the magnesium ribbon since it readily reacts with atmospheric oxygen, leading to the formation of a highly stable compound known as Magnesium Oxide (MgO). To prevent any subsequent reactions with oxygen, it becomes imperative to cleanse the ribbon and remove the MgO layer.
2. Write a balanced equation for the following chemical reactions.
i) Hydrogen + Chloride —-> Hydrogen chloride
ii) Barium chloride + Aluminium sulphate —-> Barium sulphate + Aluminium chloride
iii) Sodium + Water —-> Sodium hydroxide + Hydrogen
Solution:
i) H2 + Cl2 → 2HCl
ii) 3BaCl2 + Al2(SO4)3 →3BaSO4 + 2AlCl3
iii) 2Na + 2H2O → 2NaOH + H2
3. Write a balanced chemical equation with state symbols for the following reactions
i) Solutions of Barium chloride and Sodium sulphate in water react to give insoluble Barium sulphate and solution of Sodium chloride.
ii) Sodium hydroxide solution in water reacts with the hydrochloric acid solution to produce Sodium chloride solution and water.
Solution:
i) BaCl2 + Na2SO4 → BaSO4 + 2NaCl
ii) NaOH + HCl → NaCl + H2O
Chemical Equations and Reactions Class 10: Set 2, Page number – 10
1. A solution of a substance, ‘X,’ is used for whitewashing.
(i) Name the substance ‘X’ and write its formula.
(ii) Write the reaction of the substance ‘X’ named in (i) above with water.
Solution:
i) The substance ‘X’ which is used in whitewashing is quick lime or Calcium Oxide and its formula is CaO.
ii) CaO + H2O → Ca(OH)2
2. Why is the amount of gas collected in one of the test tubes in Activity 1.7 double the amount collected in the other? Name this gas.
Solution:
In activity 1.7, there is a notable difference in the amount of gas collected between two test tubes. This variance occurs because water undergoes hydrolysis, resulting in the release of H2 and O2 gases. During electrolysis, two molecules of hydrogen and one molecule of oxygen gas are generated. It explains why the quantity of hydrogen collected is twice that of oxygen.
Chemical Equations and Reactions Class 10: Set 3, Page number – 13
1. Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Solution:
When immersing an iron nail in the copper sulphate solution, a displacement reaction occurs wherein iron displaces copper from the copper sulphate compound due to iron’s higher reactivity compared to copper. Consequently, the color of the copper sulphate solution changes. The reaction can be represented as:
Fe + CuSO4 → FeSO4 + Cu
2. Give an example of a double displacement reaction other than the one given in Activity 1.10.
Solution:
The interaction between silver nitrate (AgNO3) and sodium chloride (NaCl) exemplifies a double displacement reaction. In this reaction, the negative and positive ions exchange places, leading to the creation of a white precipitate called silver chloride (AgCl). The chemical equation representing this process is as follows:
Ag+ + NO3– + Na+ + Cl– → AgCl + Na+ + NO3–
3. Identify the substances that are oxidised and that are reduced in the following equation.
i) 4Na(s) + O2(g) → 2Na2O(s)
ii) CuO(s) + H2(g) → Cu(s) + H2O(l)
Solution:
In the first equation, Sodium (Na) undergoes oxidation upon reacting with Oxygen (O2), while in the second equation, Copper (Cu) gets reduced as a result of its reaction with Hydrogen (H2).
Chemical Equations and Reactions Class 10: Exercise Questions (Q 1 to Q 5)
1. Which of the statements about the reaction below are incorrect?
2PbO(s) + C(s) → 2Pb(s) + CO2(g)
(a) Lead is getting reduced
(b) Carbon Dioxide is getting oxidised
(c) Carbon is getting oxidised
(d) Lead oxide is getting reduced
(i) (a) and (b)
(ii) (a) and (c)
(iii) (a), (b) and (c)
(iv) all the above
Solution:
(i) (a) and (b)
2. Fe2O3 + 2Al → Al2O3 + 2Fe
The above reaction is an example of a
- Combination reaction
- Double displacement reaction
- Decomposition reaction
- Displacement reaction
Answer:
4. Displacement reaction.
3. What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer.
- Hydrogen gas and Iron chloride are produced.
- Chlorine gas and Iron hydroxide are produced.
- No reaction takes place.
- Iron salt and water are produced.
Answer: 1. Hydrogen gas and Iron chloride are produced.
4. What is a balanced chemical equation? Why should a chemical equation be balanced?
Answer:
A balanced equation ensures that the count of distinct atoms on both the reactant and product sides is identical. Balancing chemical equations is very important to follow the Law of Conservation of Mass. According to this law matter can’t be created or destroyed during a chemical reaction. Balancing equations doesn’t have a set way to do it, so people try different methods until they find the right one that works.
5. Translate the following statements into chemical equations and balance them.
(a) Hydrogen gas combines with nitrogen to form ammonia.
(b) Hydrogen sulphide gas burns in the air to give water and sulphur dioxide.
(c) Barium chloride reacts with aluminium sulphate to give Aluminium chloride and a precipitate of barium sulphate.
(d) Potassium metal reacts with water to give potassium hydroxide and Hydrogen gas.
Solution:
(a) Unbalanced: H2 + N2 → NH3
Balanced: 3H2 + N2 → 2NH3
(b) Unbalanced: H2S + O2 → H2O + SO2
Balanced: 2H2S + 3O2 → 2H2O + 2SO2
(c) Unbalanced:
BaCl2 + Al2(SO4)3 → AlCl3 + BaSO4
Balanced: 3BaCl2 + Al2(SO4)3 → 2AlCl3 + 3BaSO4
(d) Unbalanced: K + H2O → KOH + H2
Balanced: 2K + 2H2O → 2KOH + H2
Chemical Equations and Reactions Class 10: Exercise Questions (Q 6 to Q 10)
6. Balance the following chemical equations.
(a) HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O
(b) NaOH + H2SO4 → Na2SO4 + H2O
(c) NaCl + AgNO3 → AgCl + NaNO3
(d) BaCl2 + H2SO4 → BaSO4 + HCl
Solution:
(a) 2HNO3 + Ca(OH)2 → Ca(NO3)2 + 2H2O
(b) 2NaOH + H2SO4 → Na2SO4 + 2H2O
(c) NaCl + AgNO3 → AgCl + NaNO3
(d) BaCl2 + H2SO4 → BaSO4 + 2HCl
7. Write the balanced chemical equation for the following reactions.
Calcium hydroxide + Carbon dioxide —-> Calcium carbonate + Water
Zinc + Silver nitrate —-> Zinc nitrate + Silver
Aluminium + Copper chloride —-> Aluminium chloride + Copper
Barium chloride + Potassium sulphate —-> Barium sulphate + Potassium chloride
Solution:
2Ca(OH)2 + 2CO2 → 2CaCO3 + 2H2O
Zn + 2AgNO3 → Zn(NO3)2 + 2Ag
2Al + 3CuCl2 → 2AlCl3 + 3Cu
BaCl2 + K2SO4 → BaSO4 + 2KCl
8. Write a balanced chemical equation for the following and identify the type of reaction of each case.
KBr + BaI2 → KI + BaBr2
ZnCO3 → ZnO + CO2
H2 + Cl → HCl
Mg + HCl → MgCl2 + H2
Solution:
2KBr + BaI2 → 2KI + BaBr2 (Double Displacement Reaction)
ZnCO3 → ZnO + CO2 (Decomposition Reaction)
H2 + Cl → 2HCl (Combination Reaction)
Mg + 2HCl → MgCl2 + H2 (Displacement Reaction)
9. What is meant by exothermic and endothermic reactions? Give examples.
Answer:
An endothermic reaction takes place when the system absorbs energy from the surroundings, primarily in the form of heat. Examples of endothermic reactions include processes like photosynthesis, melting of ice, and evaporation.
On the other hand, an exothermic reaction is characterized by the release of energy from the system into the surroundings. Instances of exothermic reactions encompass events such as explosions, concrete setting, and nuclear fission and fusion.
10. Why is respiration considered to be an exothermic reaction?
Answer:
Energy is essential for the sustenance of life, and we acquire it from the food we consume. During digestion, the food molecules are broken down into simpler substances, such as glucose.
When these substances interact with the oxygen present in our body cells, they produce carbon dioxide and water, along with a certain amount of energy (a process known as respiration).
Since this energy is in the form of heat, which helps maintain our body temperature, respiration is classified as an exothermic reaction. The equation is describe as:
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
Chemical Equations and Reactions Class 10: Exercise Questions (Q 11 to Q 15)
11. Why are decomposition reactions called the opposite of Combination reactions? Write equations for decomposition reactions.
Answer:
A combination reaction involves the interaction of two or more molecules to create a larger molecule, whereas a decomposition reaction refers to the breakdown of larger molecules into two or more smaller molecules. Essentially, the decomposition reaction stands as the reverse process of a combination reaction.
In lots of cases, the decomposition reaction needs heat from the surroundings or added heat to break the bonds of the larger molecule. This makes it an endothermic reaction. A few examples of decomposition reactions include: [Here you can list the examples of decomposition reactions]
ZnCO3 → ZnO + CO2
CaCO3 + Energy → CaO + CO2
2HgO → 2Hg + O2
12. Write one equation each for decomposition reactions in which energy is supplied in the form of heat, light or electricity.
Answer:
(a) Thermal decomposition reaction (Thermolysis)
2KClO3 + Heat → 2KCl + 3O2
(b) Electrolytic decomposition reaction (Electrolysis)
2NaCl → 2Na + Cl2
(c) Photodecomposition reaction (Photolysis)
2H2O2 → 2H2O
13. What is the difference between displacement and double displacement reactions? Write relevant equations for the above.
Solution:
A displacement reaction occurs when a more reactive substance displaces a less reactive one from its salt solution, whereas a double displacement reaction involves a mutual exchange of ions between two compounds.
In a displacement reaction, a single displacement occurs, whereas in the double displacement reaction, as the name suggests, two displacements take place between the molecules.
Examples:
Displacement reaction:
Mg + 2HCl → MgCl2 + H2
Double displacement reaction:
2KBr + BaI2 → 2KI + BaBr2
14. In the refining of Silver, the recovery of silver from Silver nitrate solution involves displacement reaction by Copper metal. Write down the reaction involved.
Solution:
Cu(s) + 2AgNO3(aq) → Cu(NO3)2(aq) + 2Ag(s)
15. What do you mean by a precipitation reaction? Explain by giving examples.
Solution:
When we mix two solutions that have dissolvable salts, a special reaction called double displacement happens. In this reaction, the ions in the compounds switch places with each other. If one of the compounds formed in this reaction is in a solid form and insoluble in the aqueous solution, it settles down at the bottom of the container. Here are a few examples of precipitation reactions:
Example 1:
CdSO4(aq) + K2S(aq) → CdS(s) + K2SO4(aq)
Example 2:
2NaOH(aq) + MgCl2(aq) → 2NaCl(aq) + Mg(OH)2(s)
Chemical Equations and Reactions Class 10: Exercise Questions (Q 16 to Q 20)
16. Explain the following in terms of the gain of oxygen with two examples each.
(a) Oxidation
(b) Reduction
Solution:
(a) In a chemical reaction, when oxygen combines with an element to form its corresponding oxide, the element is undergoing oxidation. Examples:
1. 4Na(s) + O2(g) → 2Na2O(s)
In this reaction, sodium (Na) is being oxidized as it combines with oxygen (O2) to form sodium oxide (Na2O).
2. H2S + O2 → H2O + SO2
Here, hydrogen sulfide (H2S) is oxidized by oxygen (O2) to produce water (H2O) and sulfur dioxide (SO2).
(b) In a chemical reaction, when oxygen is removed from a compound, it is considered to be reduced. Examples:
1. CuO(s) + H2(g) → Cu(s) + H2O(l)
In this reaction, copper oxide (CuO) is reduced as it loses oxygen, and hydrogen gas (H2) is oxidized to form water (H2O).
2. 2HgO → 2Hg + O2
In this case, mercury oxide (HgO) is reduced as it gives up oxygen, resulting in the production of mercury (Hg), and the released oxygen (O2) becomes a separate gas.
17. A shiny brown coloured element ‘X’ on heating in the air becomes black in colour. Name the element ‘X’ and the black-coloured compound formed.
Solution:
The lustrous, brown-colored element is Copper metal (Cu). When we heat this metal while it is near air, it reacts with the oxygen in the air. This reaction makes copper oxide. Therefore, the black-colored compound obtained is copper oxide.
The chemical equation representing the reaction is:
2Cu(s) + O2(g) → 2CuO(s)
18) Why do we apply paint on iron articles?
Solution:
Iron particles are coated with paint to safeguard them from rusting. When left unpainted, the metal surface comes into contact with atmospheric oxygen and, in the presence of moisture, forms Iron(III) oxide, commonly known as rust. But when we paint the surface, it stays protected from water and air. This stops rusting from happening and keeps the object safe.
19) Oil and Fat containing food items are flushed with Nitrogen. Why?
Solution:
The primary objective of flushing Nitrogen into food packets containing oil and fat items is to inhibit rancidity. Rancidity occurs when the oil or fat reacts with oxygen, resulting in an unpleasant smell and taste. When we put Nitrogen into the packets, it creates a special environment where things don’t react much. This stops rancidity from happening and keeps the items fresh for a longer time.
20) Explain the following terms with one example each.
(a) Corrosion
(b) Rancidity
Solution:
(a) Corrosion is a natural process where a refined metal undergoes oxidation upon exposure to atmospheric oxygen, resulting in the formation of more stable compounds like oxides. Over time, the metal gradually degrades during the corrosion process. A common example of corrosion is the rusting of iron, which happens when iron turns into iron oxide. Preventing rusting is very important because it can cause damage to bridges and monuments, leading to millions of dollars spent each year to protect them from harm.
(b) Rancidity refers to the condition caused by the aerial oxidation of oil and fat present in food materials, leading to an unpleasant taste and smell. To slow down this process of degradation, you can put the food in the refrigerator. The cold temperature stops the reaction that causes the unpleasant taste and smell, keeping the food fresh and good to eat.
NCERT Solutions for Science Chapter 1 Chemical Equations and Reactions Class 10
“Chemical Reactions and Equations” is a foundational chapter that imparts fundamental knowledge about chemical reactions and equations. It is essential for students to grasp the concepts in this chapter as it forms the basis for understanding more advanced topics in chemistry. If you want to study science, especially in higher secondary school, it’s highly recommended to become very familiar with this chapter. The concepts learned here will hold great importance and relevance throughout their academic journey.
Features of NCERT Solutions for Chapter 1 Science Chemical Equations and Reactions Class 10
By engaging in comprehensive practice, students can refine their skills in balancing various types of equations.
NCERT Solutions play a crucial role in guiding students to write chemical equations correctly, offering valuable assistance.
Thoroughly working through NCERT Solutions, which involve solving questions of different levels of difficulty, can effectively prepare students for the CBSE examination.
Chemical reactions are integral to our lives. It is observed in the rusting of iron, curdling of milk, respiration, digestion, and growth.
To do well in the CBSE Class 10 examination, students should focus on practicing the NCERT Solutions for Chemical Equations and Reactions Class 10, which are available here.
Frequently Asked Question – FAQs on Chemical Equations and Reactions Class 10
Q 1. What are 10 chemical reactions examples?
Certainly! Here are 10 chemical reaction examples:
- Combustion of methane: CH4 + 2O2 → CO2 + 2H2O
- Photosynthesis: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2
- Rusting of iron: 4Fe + 3O2 + 6H2O → 4Fe(OH)3
- Decomposition of hydrogen peroxide: 2H2O2 → 2H2O + O2
- Formation of table salt (sodium chloride): Na + Cl2 → 2NaCl
- Acid-base neutralization: HCl + NaOH → NaCl + H2O
- Fermentation of glucose: C6H12O6 → 2C2H5OH + 2CO2
- Synthesis of water: 2H2 + O2 → 2H2O
- Precipitation reaction: AgNO3 + NaCl → AgCl + NaNO3
- Single displacement reaction: Zn + CuSO4 → ZnSO4 + Cu
Keep in mind that these are simplified representations of the reactions, and in practice, various factors and conditions can influence the reactions.
Q 2. What are the 4 types of chemical equations?
The four main types of chemical equations are:
1. Combination (Synthesis) Reactions: In these reactions, two or more substances combine to form a single product. The general form of a combination reaction is:
A + B → AB
2. Decomposition Reactions: In decomposition reactions, a single compound breaks down into two or more simpler substances. The general form of a decomposition reaction is:
AB → A + B
3. Single Displacement (Replacement) Reactions: In single displacement reactions, an element replaces another element in a compound, leading to the formation of a new compound and a different element. The general form of a single displacement reaction is:
A + BC → AC + B
4. Double Displacement (Metathesis) Reactions: In double displacement reactions, the positive and negative ions of two compounds exchange places, leading to the formation of two new compounds. The general form of a double displacement reaction is:
AB + CD → AD + CB
These types of chemical equations represent the various ways in which chemical reactions can occur and are essential for understanding the behavior of substances during chemical transformations.
Q 3. How many chemical formulas are there in Chemical Equations and Reactions Class 10?
The number of chemical formulas is virtually infinite because there are countless possible combinations of elements that can form different compounds. Each unique chemical compound has its own distinct chemical formula, which represents the types and proportions of atoms present in the compound.
Chemical formulas are a concise and standardized way to represent chemical compounds, and they follow specific rules to convey information about the elements and their relative ratios in the compound. As scientists continue to discover and synthesize new compounds, the number of chemical formulas continues to grow. While it is not possible to determine an exact count of all possible chemical formulas, the diversity of compounds is a fundamental aspect of the vast and intricate field of chemistry.
Q 4. Which is the best example of a chemical reaction?
One of the best and most well-known examples of a chemical reaction is the combustion of methane (CH4) with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O). The reaction complete combustion of methane represented by the following chemical equation:
CH4 + 2O2 → CO2 + 2H2O
In this reaction, methane (a hydrocarbon) reacts with oxygen gas in the presence of heat or a flame. The result is the complete transformation of the reactants (methane and oxygen) into the products (carbon dioxide and water). This reaction releases a significant amount of energy in the form of heat and light, making it an essential process for various applications, including cooking, heating, and power generation.
The combustion of methane is a fundamental example of a chemical reaction that showcases the rearrangement of atoms and the formation of new substances with distinct properties from the original reactants.
Q 5. Use of chemical reaction in daily life according to Chemical Equations and Reactions Class 10?
Chemical reactions are an integral part of our daily lives, impacting various processes and activities. Combustion, such as burning fuels for cooking and transportation, releases heat and light through chemical reactions.
Photosynthesis in plants converts carbon dioxide and water into glucose and oxygen, sustaining life. Respiration in our bodies utilizes chemical reactions to produce energy and expel carbon dioxide. During digestion, chemical reactions break down food for nutrient absorption. Rusting occurs as metals react with oxygen and moisture. Baking involves reactions between ingredients, causing dough or batter to rise.
Fermentation creates products like yogurt and alcoholic beverages through microbial reactions. Cleaning products work by chemical reactions to remove dirt and stains. Batteries operate through chemical reactions to generate electrical energy. Additionally, pharmaceuticals use chemical reactions to produce medicines for treating diseases. These examples illustrate how chemical reactions play a vital role in our daily activities and advancements in modern life.