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Ch.19 - Electrochemistry
Chapter 19, Problem 49b

Balance the following half-reactions. (b) (basic) Ni(OH)2(s) → Ni2O3(s)

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Identify the elements that are changing oxidation states. Here, nickel (Ni) is the element undergoing a change.
Write the oxidation half-reaction for nickel. Determine the change in oxidation state for Ni from Ni(OH)_2 to Ni_2O_3.
Balance the number of Ni atoms on both sides of the equation. Since there are two Ni atoms in Ni_2O_3, you need two Ni(OH)_2 on the reactant side.
Balance the oxygen atoms by adding water (H_2O) molecules to the side that needs more oxygen. In this case, add water to the reactant side to balance the oxygen atoms.
Balance the hydrogen atoms by adding hydroxide ions (OH^-) to the side that needs more hydrogen. This will also help to balance the charge in a basic solution.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Half-Reaction Method

The half-reaction method involves separating oxidation and reduction processes to balance redox reactions. Each half-reaction is balanced for mass and charge, allowing for a clearer understanding of electron transfer. This method is particularly useful in complex reactions, such as those occurring in basic or acidic solutions.
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Balancing in Basic Solutions

When balancing reactions in basic solutions, hydroxide ions (OH⁻) are used to neutralize any hydrogen ions (H⁺) that appear during the balancing process. This often involves adding water molecules to balance oxygen atoms and then adding OH⁻ to balance any resulting H⁺ ions, ensuring that the final equation reflects the basic conditions.
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Oxidation States

Oxidation states are a way to keep track of electron transfer in redox reactions. Each element in a compound is assigned an oxidation state based on its electron configuration and bonding. Understanding oxidation states is crucial for identifying which species are oxidized and reduced, thus aiding in the balancing of half-reactions.
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Oxidation Numbers