AP Chem, balance Redox equation

• gigi9
In summary, a redox reaction involves the transfer of electrons between elements and can be identified by changes in oxidation numbers and the presence of reducing or oxidizing agents. To balance a redox equation, one must balance the atoms and charges, and ensure that the number of electrons transferred is equal on both sides. Balancing a redox equation ensures conservation of mass and charge. Common mistakes to avoid include forgetting to add electrons, incorrect atom balancing, and not considering oxidation states. An example of balancing a redox equation is shown with the equation: Cr2O7^2- + 6Fe^2+ → 2Cr^3+ + 6Fe^3+.
gigi9
Please help me w/ the 2 redox equations. Show me how to assign the oxidation # and how to do it please, especially the 1st problem. The problems are attached. Thank you very much for ur time.

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• redox.doc
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Below attachment is my redox equation

Sure, I'd be happy to help with balancing redox equations. First, let's review the steps for balancing a redox equation:

1. Assign oxidation numbers to all elements in the equation.
2. Identify the element that is undergoing oxidation and the element that is undergoing reduction.
3. Write separate half-reactions for the oxidation and reduction processes.
4. Balance the number of atoms on each side of the equation.
5. Balance the charges by adding electrons to one side of the equation.
6. Make sure the total charge and number of atoms are balanced on both sides.
7. If necessary, add H+ or OH- ions to balance the hydrogen and oxygen atoms.
8. Combine the half-reactions and simplify if possible.
9. Check that the charges and atoms are balanced on both sides.

Now, let's apply these steps to the two equations you provided:

Problem 1:
Fe2O3 + Al → Fe + Al2O3

Step 1: Assign oxidation numbers to all elements.
Fe2O3: Fe has an oxidation number of +3 and O has an oxidation number of -2.
Al: Al has an oxidation number of 0.
Fe: Fe has an oxidation number of 0.
Al2O3: Al has an oxidation number of +3 and O has an oxidation number of -2.

Step 2: Identify the element undergoing oxidation and reduction.
In this case, Fe is being reduced from +3 to 0 and Al is being oxidized from 0 to +3.

Step 3: Write separate half-reactions.
Reduction: Fe2O3 → Fe
Oxidation: Al → Al2O3

Step 4: Balance the number of atoms.
Reduction: Fe2O3 → 2Fe
Oxidation: 2Al → Al2O3

Step 5: Balance the charges.
Reduction: Fe2O3 + 3e- → 2Fe
Oxidation: 2Al → 2Al3+ + 6e-

Step 6: Make sure the total charge and number of atoms are balanced.
Reduction: Fe2O3 + 3e- → 2Fe
Oxidation: 2Al → 2Al3+ + 6e-
Overall: Fe2O3 + 2Al → 2Fe + 2Al3+

Step

1. How do I identify a redox reaction?

A redox reaction involves the transfer of electrons between two or more elements. Look for changes in oxidation numbers and the presence of reducing or oxidizing agents to identify a redox reaction.

2. How do I balance a redox equation?

To balance a redox equation, start by balancing the atoms of each element, then balance the charges by adding electrons to one side of the equation. Finally, make sure that the number of electrons transferred is equal on both sides of the equation.

3. What is the purpose of balancing a redox equation?

The purpose of balancing a redox equation is to ensure that the number of atoms and charges are conserved and that the reaction follows the law of conservation of mass and charge.

4. What are some common mistakes to avoid when balancing redox equations?

Some common mistakes to avoid when balancing redox equations include forgetting to add the electrons, not balancing the atoms correctly, and not considering the oxidation states of each element.

5. Can you provide an example of balancing a redox equation?

For example, let's balance the equation: Cr2O72- + Fe2+ → Cr3+ + Fe3+ First, balance the atoms: Cr2O72- + 6Fe2+ → 2Cr3+ + 6Fe3+ Next, balance the charges: Cr2O72- + 6Fe2+ + 14H+ → 2Cr3+ + 6Fe3+ + 7H2O Finally, balance the electrons: Cr2O72- + 6Fe2+ + 14H+ → 2Cr3+ + 6Fe3+ + 7H2O + 6e- The balanced equation is: Cr2O72- + 6Fe2+ + 14H+ → 2Cr3+ + 6Fe3+ + 7H2O + 6e- + 6e-

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