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Questions and Answers
In a redox reaction, when an atom or ion increases in oxidation number, it is ____ electrons and acting as _____.
Which of the following best describes an oxidizing agent in a redox reaction?
What happens to the oxidation number of an atom that is being reduced in a redox reaction?
In the redox reaction provided, what is the reducing agent?
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Which species in a redox reaction has an increase in oxidation number?
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What role does silver play in the given redox reaction?
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How is the reduction of an atom or ion determined in a redox reaction?
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What is the role of zinc in the given redox reaction?
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What happens to the oxidation number of silver during the given redox reaction?
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Which species undergoes reduction in the provided redox reaction?
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Study Notes
Redox Reactions: Unpacking Electron Transfers in Chemical Equations
Redox reactions, short for reduction–oxidation reactions, are fundamental processes occurring whenever electrons are transferred between chemical species during a chemical transformation. Understanding redox reactions requires unraveling the intricate dance of electron transfers hidden within chemical equations.
A simple redox reaction might look like this: [ \ce{Zn (s)} + \ce{2 Ag+ (aq)} \longrightarrow \ce{Zn^2+ (aq)} + \ce{2 Ag (s)} ] In this example, zinc metal loses electrons and becomes zinc(II) ion ((\mathrm{Zn^{2+}})). Simultaneously, silver(II) ions gain electrons and become metallic silver. Silver acts as an oxidizing agent, while zinc behaves as a reducing agent.
To determine which half of the reaction involves loss or gain of electrons, follow these conventions:
- An atom or ion increases in oxidation number is losing electrons (oxidized) and acting as an oxidizing agent.
- An atom or ion decreases in oxidation number is gaining electrons (reduced) and acting as a reducing agent.
Balanced chemical equations reveal these electronic shifts explicitly via superscripts indicating charges. For instance:
- Zinc begins with an oxidation number of zero and ends up with a charge of +2, so it gains two electrons. Thus, zinc is reduced.
- Silver starts with a charge of +2 and finishes without a charge, suggesting it gained two electrons, making it reduced too.
- Zinc acts as an oxidizing agent since it forces the silver to accept electrons.
- Similarly, silver acts as a reducing agent since it attracts electrons away from zinc.
Redox reactions play critical roles across science and engineering due to their ubiquity: batteries operate based on intentional redox cycling, corrosion is accelerated via unwanted redox events, and photosynthetic organisms carry out redox reactions involving sunlight to create biomass. Therefore, understanding redox reactions helps us comprehend diverse phenomena and develop technologies.
Lastly, remember that not every chemical reaction is a redox reaction! Only those accompanied by electron transfer qualify as such.
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Description
Explore the world of redox reactions, where electrons are transferred between chemical species during transformations. Learn how to identify oxidizing and reducing agents by analyzing oxidation numbers in balanced chemical equations.
