Define oxidation in terms of (i) electron transfer, (ii) change in oxidation number - Leaving Cert Chemistry - Question (b) - 2008
Question (b)
Define oxidation in terms of (i) electron transfer, (ii) change in oxidation number.
(iii) For the redox reactions shown below, use oxidation numbers to identify th... show full transcript
Worked Solution & Example Answer:Define oxidation in terms of (i) electron transfer, (ii) change in oxidation number - Leaving Cert Chemistry - Question (b) - 2008
Step 1
Define oxidation in terms of (i) electron transfer
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Answer
Oxidation can be defined as the loss (decrease) of electrons from a species. During this process, the oxidation state of the chemical species increases.
Step 2
Define oxidation in terms of (ii) change in oxidation number
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Answer
Oxidation is also characterized by an increase in the oxidation number of a chemical species. As electrons are lost, the oxidation number rises, indicating a higher valence state.
Step 3
Identify the species oxidised in the first reaction
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Answer
In the first reaction, the iodide ion (I⁻) is oxidised to iodine (I₂). The oxidation number of iodine increases from -1 to 0 as it forms diatomic iodine.
Step 4
Identify the oxidising reagent in the second reaction
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Answer
The oxidising reagent in the second reaction is the iodine molecule (I₂). It is reduced to iodide ion (I⁻), resulting in a decrease in its oxidation number from 0 to -1.
Step 5
Using oxidation numbers or otherwise balance both equations
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Answer
For the first reaction:
ClO⁻ + 2I⁻ → Cl⁻ + I₂ + H₂O
The oxidation states show Cl going from +1 to -1 and I from -1 to 0.
For the second reaction:
I₂ + 2SO₄²⁻ → 2I⁻ + SO₄²⁻
Here, I goes from 0 in I₂ to -1 in I⁻, while S in SO₄ remains at +6.
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