Textbook Question
Balance each redox reaction occurring in basic aqueous solution. a. MnO4–(aq) + Br–(aq) → MnO2(s) + BrO3–(aq)
Ch.19 - Electrochemistry
Chapter 19, Problem 43
Sketch a voltaic cell for each redox reaction. Label the anode and cathode and indicate the half-reaction that occurs at each electrode and the species present in each solution. Also indicate the direction of electron flow.
a. 2 Ag+(aq) + Pb(s) → 2 Ag(s) + Pb2+(aq)
b. 2 ClO2(g) + 2 I–(aq) → 2 ClO2–(aq) + I2(s)
c. O2(g) + 4 H+(aq) + 2 Zn(s) → 2 H2O(l) + 2 Zn2+(aq)
Verified step by step guidance1
Step 1: Identify the oxidation and reduction half-reactions for each redox reaction. For reaction (a), Ag+ is reduced to Ag, and Pb is oxidized to Pb2+. For reaction (b), ClO2 is reduced to ClO2-, and I- is oxidized to I2. For reaction (c), O2 is reduced to H2O, and Zn is oxidized to Zn2+.
Step 2: Determine the anode and cathode for each reaction. The anode is where oxidation occurs, and the cathode is where reduction occurs. For reaction (a), Pb is the anode and Ag+ is the cathode. For reaction (b), I- is the anode and ClO2 is the cathode. For reaction (c), Zn is the anode and O2 is the cathode.
Step 3: Write the half-reactions for each electrode. For reaction (a), the anode half-reaction is Pb(s) → Pb2+(aq) + 2e-, and the cathode half-reaction is Ag+(aq) + e- → Ag(s). For reaction (b), the anode half-reaction is 2 I-(aq) → I2(s) + 2e-, and the cathode half-reaction is ClO2(g) + e- → ClO2-(aq). For reaction (c), the anode half-reaction is Zn(s) → Zn2+(aq) + 2e-, and the cathode half-reaction is O2(g) + 4 H+(aq) + 4e- → 2 H2O(l).
Step 4: Indicate the species present in each solution. For reaction (a), the anode solution contains Pb2+ ions, and the cathode solution contains Ag+ ions. For reaction (b), the anode solution contains I- ions, and the cathode solution contains ClO2- ions. For reaction (c), the anode solution contains Zn2+ ions, and the cathode solution contains H+ ions.
Step 5: Indicate the direction of electron flow. Electrons flow from the anode to the cathode in each voltaic cell. For reaction (a), electrons flow from Pb to Ag+. For reaction (b), electrons flow from I- to ClO2. For reaction (c), electrons flow from Zn to O2.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Voltaic Cell Structure
A voltaic cell, also known as a galvanic cell, consists of two half-cells connected by a salt bridge. Each half-cell contains an electrode immersed in an electrolyte solution. The anode is where oxidation occurs, releasing electrons, while the cathode is where reduction takes place, accepting electrons. Understanding this structure is essential for sketching the cell and labeling its components correctly.
Recommended video:
Guided course
01:21
The Electrolytic Cell
Redox Reactions
Redox reactions involve the transfer of electrons between two species, where one species is oxidized (loses electrons) and the other is reduced (gains electrons). In the provided reactions, identifying the oxidation states and determining which species undergoes oxidation and reduction is crucial for labeling the anode and cathode correctly. This concept is fundamental to understanding the electron flow in a voltaic cell.
Recommended video:
Guided course
03:12Identifying Redox Reactions
Electron Flow Direction
In a voltaic cell, electrons flow from the anode to the cathode through an external circuit. This flow is driven by the difference in potential energy between the two electrodes, with electrons moving from the oxidized species at the anode to the reduced species at the cathode. Accurately indicating the direction of electron flow is vital for a complete understanding of the cell's operation and the underlying redox processes.
Recommended video:
Guided course
03:56Electron Geometry
Related Practice
Textbook Question
Balance each redox reaction occurring in basic aqueous solution. b. Ag(s) + CN–(aq) + O2(g) → Ag(CN)2–(aq)
Textbook Question
Balance each redox reaction occurring in basic aqueous solution. c. NO2–(aq) + Al(s) → NH3(g) + AlO2–(aq)
Textbook Question
Sketch a voltaic cell for each redox reaction. Label the anode and cathode and indicate the half-reaction that occurs at each electrode and the species present in each solution. Also indicate the direction of electron flow. a. Ni2+(aq) + Mg(s) → Ni(s) + Mg2+(aq)
Textbook Question
Sketch a voltaic cell for each redox reaction. Label the anode and cathode and indicate the half-reaction that occurs at each electrode and the species present in each solution. Also indicate the direction of electron flow.
b. 2 H+(aq) + Fe(s) → H2(g) + Fe2+(aq)
c. 2 NO3–(aq) + 8 H+(aq) + 3 Cu(s) → 2 NO(g) + 4 H2O(l) + 3 Cu2+(aq)
Textbook Question
Calculate the standard cell potential for each of the electro- chemical cells in Problem 43.