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Chapter Analysis
Intermediate16 pages • EnglishQuick Summary
Chapter 1 of Class 10 Science titled 'Chemical Reactions and Equations' discusses the transformation of substances during chemical reactions. It covers the importance of balanced chemical equations and introduces different types of reactions such as combination, decomposition, displacement, and double displacement. Throughout the chapter, concepts like oxidation, reduction, and the conservation of mass are explained through various examples and activities.【4:16†source】
Key Topics
- •Balanced Chemical Equations
- •Types of Chemical Reactions
- •Combination Reactions
- •Oxidation and Reduction
- •Decomposition Reactions
- •Displacement Reactions
- •Double Displacement Reactions
- •Conservation of Mass
Learning Objectives
- ✓Understand the necessity of balancing chemical equations.
- ✓Identify different types of chemical reactions.
- ✓Explain oxidation and reduction processes.
- ✓Differentiate between combination and decomposition reactions.
- ✓Describe the significance of displacement reactions.
- ✓Comprehend the principle of conservation of mass in reactions.
Questions in Chapter
Which of the statements about the reaction 2PbO(s) + C(s) → 2Pb(s) + CO2(g) are incorrect?
Page 15
What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer.
Page 15
What is a balanced chemical equation? Why should chemical equations be balanced?
Page 15
Translate the following statements into chemical equations and then balance them. (i) Hydrogen gas combines with nitrogen to form ammonia. (ii) Hydrogen sulphide gas burns in air to give water and sulpur dioxide. (iii) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate. (iv) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.
Page 15
Balance the following chemical equations. (i) HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O (ii) NaOH + H2SO4 → Na2SO4 + H2O (iii) NaCl + AgNO3 → AgCl + NaNO3 (iv) BaCl2 + H2SO4 → BaSO4 + HCl
Page 15
Write the balanced chemical equations for the following reactions. (i) Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water (ii) Zinc + Silver nitrate → Zinc nitrate + Silver (iii) Aluminium + Copper chloride → Aluminium chloride + Copper (iv) Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride
Page 15
Write the balanced chemical equation for the following and identify the type of reaction in each case. (i) Potassium bromide(aq) + Barium iodide(aq) → Potassium iodide(aq) + Barium bromide(s) (ii) Zinc carbonate(s) → Zinc oxide(s) + Carbon dioxide(g) (iii) Hydrogen(g) + Chlorine(g) → Hydrogen chloride(g) (iv) Magnesium(s) + Hydrochloric acid(aq) → Magnesium chloride(aq) + Hydrogen(g)
Page 16
What does one mean by exothermic and endothermic reactions? Give examples.
Page 16
Why is respiration considered an exothermic reaction? Explain.
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Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
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Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.
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What is the difference between displacement and double displacement reactions? Write equations for these reactions.
Page 16
In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.
Page 16
What do you mean by a precipitation reaction? Explain by giving examples.
Page 16
Explain the following in terms of gain or loss of oxygen with two examples each. (a) Oxidation (b) Reduction
Page 16
A shiny brown coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black coloured compound formed.
Page 16
Why do we apply paint on iron articles?
Page 16
Oil and fat containing food items are flushed with nitrogen. Why?
Page 16
Explain the following terms with one example each. (a) Corrosion (b) Rancidity
Page 16
Additional Practice Questions
Explain why balancing chemical equations is necessary.
mediumAnswer: Balancing chemical equations is necessary to satisfy the Law of Conservation of Mass, which states that mass cannot be created or destroyed in a chemical reaction. This ensures that the same number of each type of atom is present on both sides of the equation.
Describe what happens in an oxidation reaction.
mediumAnswer: In an oxidation reaction, a substance gains oxygen or loses hydrogen, resulting in the oxidation of the substance. For example, when magnesium burns in air, it forms magnesium oxide, gaining oxygen in the process.
What are the outcomes of a decomposition reaction?
mediumAnswer: A decomposition reaction involves a single compound breaking down into two or more simpler substances. For instance, when calcium carbonate is heated, it decomposes into calcium oxide and carbon dioxide.
Discuss the effects of oxidation reactions in daily life.
hardAnswer: Oxidation reactions can lead to corrosion, such as rusting of iron, and rancidity in food, affecting quality and shelf life. These reactions impact maintenance costs and food preservation strategies.
How do displacement reactions work in refining metals?
hardAnswer: In displacement reactions, a more reactive metal displaces a less reactive metal from its compound. This principle is used in the refining of metals, such as using copper to displace silver from silver nitrate solution to recover silver.
Explore the role of energy in chemical reactions.
mediumAnswer: Energy is either absorbed or released in chemical reactions. In exothermic reactions, energy is released, usually in the form of heat, while endothermic reactions require energy input to proceed.
Explain how double displacement reactions occur.
easyAnswer: In double displacement reactions, two compounds exchange ions to form two new compounds. An example is the reaction between sodium sulphate and barium chloride, resulting in the formation of barium sulphate and sodium chloride.
What is the significance of a chemical reaction's rate of reaction?
mediumAnswer: The reaction rate indicates how quickly reactants are converted into products, impacting industrial processes and product formation speed. Factors like temperature, concentration, and catalysts influence this rate.
Analyze the importance of equilibria in chemical reactions.
hardAnswer: Equilibria in chemical reactions indicate a balance between forward and reverse reactions, crucial for processes such as chemical manufacturing where the yield of desired products can be maximized.
How can pH affect chemical reactions?
hardAnswer: pH can alter the rate of reactions by affecting the concentration of hydrogen ions in a solution, potentially increasing or decreasing reaction rates. Enzyme activity in the body is also heavily pH-dependent.
NCERT Exemplar
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