Question

When chlorine is added to drinking water to kill bacteria, some of the chlorine is changed into ions by the following equilibrium:

Cl2(aq) + H2O H+(aq) + Cl–(aq) + HOCl(aq)

In the forward reaction (the reaction going from left to right), which substance is oxidized and which is reduced?

1- O is oxidized and Cl is reduced.

2- Cl is both reduced and oxidized.

3- Cl is oxidized and H is reduced.

4- H is both reduced and oxidized.

5- O is oxidized and H is reduced.

6- Cl is oxidized and O is reduced.

In the reverse reaction, which is the oxidizing agent and which is the reducing agent?

1- Cl- is the oxidizing agent Cl2 is the oxidizing agent

2- Cl- is the reducing agent HOCl is the reducing agent

3- H2O is the reducing agent HOCl is the oxidizing agent

4- H2O is the oxidizing agent H+ is the reducing agent

6- H+ is the oxidizing agent Cl2 is the reducing agent

Answer 1

Let us write the oxidation staate of each
Cl2(aq) + H2O ----> H+(aq) + Cl–(aq) + HOCl(aq)
0 +1 -2 +1 -1 +1 -2 +1
Cl changes it state from 0 to both +1 and -1
Hence Cl is both oxidised and reduced
Answer: 2
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oxidising agent is the one which is getting reduced
In reverse reaction: HOCl is getting reduced as Cl changes from +1 to 0
HOCl is oxiding agent

reducing agent is the one which is getting oxidised
In reverse reaction: Cl- is getting oxidised as Cl changes from -1 to 0
Cl- is reducing agent
Answer: should be 2 but I think there is typing mistake
2- Cl- is the reducing agent HOCl is the oxidising agent