Balancing Redox Reactions using half reactions?

In summary: It should just say "5ClO{-} + 4H{+} with ClO{3-} as the oxidizing agent." Yeah, but the answer key doesn't have an HClO in it at all. It should just say "5ClO{-} + 4H{+} with ClO{3-} as the oxidizing agent."
  • #1
kshah93
12
0

Homework Statement


Use half reactions to balance the following redox reactions and underline the oxidizing agent.
a) Cl2 + ClO3{-} -> ClO{-} (acidic)

{} is the charge
e{-} is electrons


Homework Equations


Not applicable


The Attempt at a Solution



Well I tried to separate and write the two half reactions:

1) Cl2 + 2e{-} -> 2Cl{-} (I took this directly from my standard reduction potentials table)

2) ClO3{-} -> ClO{-} (I attempted to balance this half-reaction as it didn't appear on my table)
4H{+} + ClO3{-} + 4e{-} -> ClO{-} + 2H2O (I added 2H2O to the right side to balance the oxygen and then added 4H{+} on the left side to balance the hydrogen, then added 4 electrons (4e{-}) to the left side to balance the charges)

Once determining both half reactions, I am stuck, and am not sure exactly how to proceed.
The answer key to this question states:

2Cl2 + ClO{3-} + 2H2O -> 5ClO{-} + 4H{+} with ClO{3-} as the oxidizing agent.

Did I approach this question incorrectly and how am I supposed to balance this redox equation using half reactions?
 
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  • #2
This might help.

Using standard reduction potential table from Wikipedia, you could find this half:

Cl2 + 2H2O <------> 2e + 2H+ + 2HClO

and other half, based on your telling from message:

4H+ + ClO3- +4e <--------> ClO- + 2H2O
 
  • #3
symbolipoint said:
This might help.

Using standard reduction potential table from Wikipedia, you could find this half:

Cl2 + 2H2O <------> 2e + 2H+ + 2HClO

and other half, based on your telling from message:

4H+ + ClO3- +4e <--------> ClO- + 2H2O

Okay, thanks for responding. I have one question. For your first half reaction, why is there an HClO?
 
  • #4
kshah93 said:
Okay, thanks for responding. I have one question. For your first half reaction, why is there an HClO?

You stated that the conditions are acidic solution. HClO is a weak acid.
 
  • #5
symbolipoint said:
You stated that the conditions are acidic solution. HClO is a weak acid.

Yeah, but the answer key doesn't have an HClO in it at all.
 

1. How do I identify redox reactions?

Redox reactions are chemical reactions in which there is a transfer of electrons between reactants. This can be identified by a change in oxidation state of the elements involved.

2. What are half reactions and why are they important in balancing redox reactions?

Half reactions are the individual reactions that occur for each element involved in a redox reaction. They are important because they allow us to break down a complex redox reaction into simpler steps, making it easier to balance.

3. How do I balance a redox reaction using half reactions?

To balance a redox reaction using half reactions, you need to first identify the oxidation and reduction half reactions. Then, balance the elements other than oxygen and hydrogen in each half reaction. Next, balance the oxygen atoms by adding water molecules, and balance the hydrogen atoms by adding hydrogen ions. Finally, balance the charge by adding electrons to one or both half reactions.

4. Can the same element be oxidized and reduced in a redox reaction?

Yes, the same element can be both oxidized and reduced in a redox reaction. This is known as self-ionization or auto-reduction.

5. Are there any rules or guidelines to follow when balancing redox reactions using half reactions?

Yes, there are a few guidelines to follow when balancing redox reactions using half reactions. These include balancing the elements other than oxygen and hydrogen first, balancing oxygen atoms by adding water molecules, balancing hydrogen atoms by adding hydrogen ions, and balancing the charge by adding electrons to one or both half reactions. Additionally, it is important to ensure that the number of electrons transferred in each half reaction is equal.

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