Textbook Question
Balance each redox reaction occurring in acidic aqueous solution. c. BrO3–(aq) + N2H4(g) → Br–(aq) + N2(g)
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Ch.19 - Electrochemistry
Chapter 19, Problem 37a,b
Balance each redox reaction occurring in acidic aqueous solution. a. K(s) + Cr3+(aq) → Cr(s) + K+(aq) b. Al(s) + Fe2+(aq) → Al3+(aq) + Fe(s)
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Identify the oxidation states of all elements in the reactants and products. Potassium (K) in its elemental form has an oxidation state of 0, Chromium (Cr) in Cr3+ has an oxidation state of +3, Chromium in Cr(s) has an oxidation state of 0, and Potassium in K+ has an oxidation state of +1.
Determine the changes in oxidation states to identify which elements are oxidized and which are reduced. Potassium (K) is oxidized as its oxidation state increases from 0 to +1. Chromium (Cr) is reduced as its oxidation state decreases from +3 to 0.
Write the half-reactions for both the oxidation and reduction processes. For oxidation: \( K(s) \rightarrow K^+(aq) + e^- \). For reduction: \( Cr^{3+}(aq) + 3e^- \rightarrow Cr(s) \).
Balance the electrons in the half-reactions. Since the reduction half-reaction involves gaining 3 electrons, multiply the oxidation half-reaction by 3 to balance the number of electrons lost and gained in both half-reactions.
Add the balanced half-reactions together and simplify to get the overall balanced equation in acidic solution: \( 3K(s) + Cr^{3+}(aq) \rightarrow 3K^+(aq) + Cr(s) \).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Redox Reactions
Redox reactions, or reduction-oxidation reactions, involve the transfer of electrons between two species. In these reactions, one species is oxidized (loses electrons) while another is reduced (gains electrons). Understanding the oxidation states of the elements involved is crucial for identifying which species undergo oxidation and reduction.
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Identifying Redox Reactions
Balancing Redox Reactions
Balancing redox reactions requires ensuring that both mass and charge are conserved. This often involves separating the reaction into half-reactions: one for oxidation and one for reduction. In acidic solutions, hydrogen ions (H+) and water (H2O) are typically added to balance the equation, along with electrons to balance the charge.
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01:04Balancing Basic Redox Reactions
Acidic Aqueous Solutions
In acidic aqueous solutions, the presence of H+ ions influences the behavior of the reactants and products. The pH of the solution can affect the solubility and reactivity of certain species. When balancing redox reactions in such environments, it is essential to account for the H+ ions and any water produced or consumed in the reaction.
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01:11Types of Aqueous Solutions