Define oxidation in terms of (i) electron transfer, (ii) change in oxidation number - Leaving Cert Chemistry - Question c) - 2014
Question c)
Define oxidation in terms of (i) electron transfer, (ii) change in oxidation number.
Use oxidation numbers to identify (iii) the oxidising agent, (iv) the reducing ... show full transcript
Worked Solution & Example Answer:Define oxidation in terms of (i) electron transfer, (ii) change in oxidation number - Leaving Cert Chemistry - Question c) - 2014
Step 1
Define oxidation in terms of (i) electron transfer
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Answer
Oxidation is defined as the process involving the loss of electrons. In a chemical reaction, when a substance loses electrons, it increases its oxidation state, which signifies that it is being oxidized.
Step 2
Define oxidation in terms of (ii) change in oxidation number
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Answer
Oxidation can also be defined as an increase in oxidation number. This increment indicates that the species is undergoing a transformation from a lower oxidation state to a higher oxidation state as a result of losing electrons.
Step 3
Use oxidation numbers to identify (iii) the oxidising agent
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In the given reaction, we assign oxidation numbers to the elements involved:
Cadmium (Cd) goes from 0 to +2.
Nitrogen in nitrate (NO3-) goes from +5 in NO3- to +2 in NO.
Thus, the oxidising agent is NO3-, as it facilitates the oxidation of cadmium by accepting electrons.
Step 4
Use oxidation numbers to identify (iv) the reducing agent
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In the same reaction, cadmium (Cd) is the reducing agent as it donates electrons, leading to its oxidation from 0 to +2. Therefore, the reducing agent is Cd.
Step 5
Hence, or otherwise, balance the equation
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To balance the equation:
Starting with:
Cd + H+ + NO3- → Cd2+ + NO + H2O
Balancing gives:
3Cd + 8H+ + 2NO3- → 3Cd2+ + 2NO + 4H2O
Thus, ensuring that both mass and charge are balanced.
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