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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.
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.
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.
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.
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-