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Chapter Analysis
Intermediate20 pages • EnglishQuick Summary
The chapter on Redox Reactions introduces the concept of redox processes, highlighting the simultaneous occurrence of oxidation and reduction. It covers different methods to balance redox reactions, including the oxidation number method and the half-reaction method. The chapter also explores various types of redox reactions such as combination, decomposition, displacement, and disproportionation. Additionally, the material delves into the applications of redox reactions in electrode processes and titrations.
Key Topics
- •Oxidation and reduction concepts
- •Oxidation numbers
- •Balancing redox reactions
- •Types of redox reactions
- •Redox titrations
- •Electrode processes and standard potentials
Learning Objectives
- ✓Identify and define redox reactions.
- ✓Use oxidation numbers to identify oxidizing and reducing agents.
- ✓Classify redox reactions into various types.
- ✓Balance chemical equations using oxidation number and half-reaction methods.
- ✓Understand the concept of electrode processes in redox reactions.
Questions in Chapter
Assign oxidation number to the underlined elements in each of the following species: (a) NaH2PO4 (b) NaHSO4 (c) H4P2O7 (d) K2MnO4 (e) CaO2 (f) NaBH4 (g) H2S2O7 (h) KAl(SO4)2.12 H2O
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What are the oxidation number of the underlined elements in each of the following and how do you rationalise your results? (a) KI3 (b) H2S4O6 (c) Fe3O4 (d) CH3CH2OH (e) CH3COOH
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Justify that the following reactions are redox reactions: (a) CuO(s) + H2(g) → Cu(s) + H2O(g) (b) Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g) (c) 4BCl3(g) + 3LiAlH4(s) → 2B2H6(g) + 3LiCl(s) + 3 AlCl3(s) (d) 2K(s) + F2(g) → 2K+F– (s) (e) 4 NH3(g) + 5 O2(g) → 4NO(g) + 6H2O(g)
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Fluorine reacts with ice and results in the change: H2O(s) + F2(g) → HF(g) + HOF(g). Justify that this reaction is a redox reaction.
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Calculate the oxidation number of sulphur, chromium and nitrogen in H2SO5, Cr2O7 2-, and NO3-. Suggest structure of these compounds.
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Additional Practice Questions
Explain why the standard electrode potential is an important measure in redox reactions.
mediumAnswer: The standard electrode potential is crucial because it indicates the relative tendency of a species to be reduced or oxidized. A negative potential indicates a strong reducing agent, whereas a positive potential suggests a strong oxidizing agent.
How can redox reactions be identified using oxidation numbers?
easyAnswer: Redox reactions can be identified by changes in oxidation numbers of reactants and products. Oxidation involves an increase in oxidation number, while reduction involves a decrease.
Differentiate between combination and decomposition redox reactions.
mediumAnswer: In combination reactions, elements combine to form a compound, while in decomposition reactions, a compound breaks down into simpler substances. Both involve changes in oxidation states.
What role do redox reactions play in biological systems?
hardAnswer: Redox reactions are vital in biological systems as they are involved in cellular respiration and photosynthesis, where energy is transferred through electron acceptor and donor molecules.
Describe a galvanic cell and its function in converting chemical energy to electrical energy.
hardAnswer: A galvanic cell consists of two half-cells connected by a salt bridge, facilitating electron flow from the oxidized species in one half-cell to the reduced species in the other, thus converting chemical energy into electrical energy.