When you reach Definition 4, you will realise that the gain or loss of electrons may not be truly the best definition for redox.
This third definition is best used in situations whereby equations are written in ionic form.
Example 1 Zn + Cu2+ → Zn2+ + Cu Zinc is more reactive than copper, thus zinc displaces copper(II) ions from its aqueous solution. Details of such displacement will be introduced in the chapter on Metals.
Based on atomic structure, each Zn atom will lose two valence electrons to form the octet, stable structure, Zn2+. Thus, Zinc has been oxidised to form Zn2+. The substance playing the role of the oxidising agent is Cu2+.
Example 2 2Fe3+ + H2S → 2Fe2+ + 2H+ + S Fe3+ gains one electron to form Fe2+. Thus, Fe3+ has been reduced and H2S is the reducing agent.
But how do we use this definition if the equation is not an ionic, but a chemical balanced equation? Then we will have to interpret the substance by "looking into the formula".
Example 3 Cl2(g) + 2KI(aq) → 2KCl(aq) + I2(aq) at this point, we will have to apply our knowledge of atomic structure and bonding before we can decide what happen to the reactants. for Cl2, two chlorine atom share their valence electrons to form a chlorine molecule. for Cl2 to become Cl- in KCl, Cl2 has to gain 2 electrons to form 2Cl-. Thus Cl2 has been reduced and KI is the reducing agent.
Read this link which summarises the three definitions of oxidation. http://www.chemguide.co.uk/inorganic/redox/definitions.html
the following video will help you to understanding more about gain and loss of electrons.
When you reach Definition 4, you will realise that the gain or loss of electrons may not be truly the best definition for redox.
This third definition is best used in situations whereby equations are written in ionic form.
Example 1
Zn + Cu2+ → Zn2+ + Cu
Zinc is more reactive than copper, thus zinc displaces copper(II) ions from its aqueous solution. Details of such displacement will be introduced in the chapter on Metals.
Based on atomic structure, each Zn atom will lose two valence electrons to form the octet, stable structure, Zn2+.
Thus, Zinc has been oxidised to form Zn2+. The substance playing the role of the oxidising agent is Cu2+.
Example 2
2Fe3+ + H2S → 2Fe2+ + 2H+ + S
Fe3+ gains one electron to form Fe2+. Thus, Fe3+ has been reduced and H2S is the reducing agent.
But how do we use this definition if the equation is not an ionic, but a chemical balanced equation?
Then we will have to interpret the substance by "looking into the formula".
Example 3
Cl2(g) + 2KI(aq) → 2KCl(aq) + I2(aq)
at this point, we will have to apply our knowledge of atomic structure and bonding before we can decide what happen to the reactants.
for Cl2, two chlorine atom share their valence electrons to form a chlorine molecule.
for Cl2 to become Cl- in KCl, Cl2 has to gain 2 electrons to form 2Cl-.
Thus Cl2 has been reduced and KI is the reducing agent.
Read this link which summarises the three definitions of oxidation.
http://www.chemguide.co.uk/inorganic/redox/definitions.html
the following video will help you to understanding more about gain and loss of electrons.
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