Skip to main content
Ch.20 - Electrochemistry
Chapter 20, Problem 84b

Consider the concentration cell: b. Indicate the direction of electron flow.

Verified step by step guidance
1
Identify the two half-cells involved in the concentration cell. A concentration cell consists of two half-cells with the same electrodes and electrolytes but different concentrations.
Determine which half-cell has the higher concentration of ions. In a concentration cell, electrons flow from the half-cell with lower ion concentration to the half-cell with higher ion concentration.
Use the Nernst equation to understand the potential difference between the two half-cells. The Nernst equation is E = E^0 - (RT/nF)ln(Q), where Q is the reaction quotient.
Recognize that the flow of electrons is from the anode to the cathode. In a concentration cell, the anode is the half-cell with the lower concentration, and the cathode is the half-cell with the higher concentration.
Conclude that the direction of electron flow is from the half-cell with lower concentration to the half-cell with higher concentration, driven by the concentration gradient.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3m
Was this helpful?

Key Concepts

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

Concentration Cell

A concentration cell is a type of electrochemical cell where two half-cells have the same electrodes but different concentrations of electrolyte solutions. The difference in concentration creates a potential difference, driving the flow of electrons from the anode (lower concentration) to the cathode (higher concentration). This setup illustrates how chemical potential can be converted into electrical energy.
Recommended video:
Guided course
01:21
The Electrolytic Cell

Electron Flow Direction

In electrochemical cells, electrons flow from the anode to the cathode. In a concentration cell, the anode is the electrode in the half-cell with the lower concentration of ions, while the cathode has the higher concentration. This flow occurs because electrons move towards the region of higher potential energy, which corresponds to the higher concentration of reactants.
Recommended video:
Guided course
03:56
Electron Geometry

Nernst Equation

The Nernst equation relates the cell potential to the concentrations of the reactants and products in an electrochemical cell. It allows for the calculation of the voltage produced by a concentration cell based on the concentration difference. Understanding this equation is crucial for predicting the direction of electron flow and the overall behavior of the cell under varying conditions.
Recommended video:
Guided course
01:17
The Nernst Equation
Related Practice