The ChemCollective   NSDL and CMU

Electrochemistry

-Introduction

Step 1:

-Investigating redox reactions

-Practice with redox reactions

-Reduction tendencies of metal ions

Step 2:

-Electron transfer

-Electrochemical cell

-Practice with cells

-Powering a stopwatch

Step 3:

-Measuring potentials

-Calculating potentials

-Practice with potentials

-Applying potentials

Step 4:

-Non-standard conditions

-Practice with non-standard cells

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Electrochemistry Tutorial: Galvanic Cells and the Nernst Equation >> Introduction

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Electrochemistry: Galvanic Cells and the Nernst Equation

Introduction


In this experiment the goal is to investigate how to generate an electric current from a spontaneous redox chemical reaction. The device in which chemical energy is changed to electrical energy is called a galvanic cell. Batteries are an everyday example of galvanic cells.

In this experiment:

    • We will build and investigate several galvanic cells.
    • We will investigate the chemical reactions taking place in various galvanic cells and measure the cell potentials.
    • We will study the electrodes that can be combined in various ways to form many different galvanic cells. We will determine the potential of these cells under standard conditions.
    • We will investigate how the potential of the galvanic cell changes when we depart from the conditions defined as a "standard" and use the Nernst Equation to predict these changes.

The experimental strategy is shown below in the following 4 steps:

    Step 1


        Action: Dip a strip of metal in a salt solution of another metal. Repeat with different metal/salt combinations.
        Result: The observations provide evidence of whether or not a spontaneous reaction takes place. If a reaction is observed, we can use our knowledge of the chemical species involved to figure out the chemical reaction.

    Step 2

        Action: Create several half-cells, each consisting of a metal strip (an electrode) dipped in solution of that metal’s salt (an electrode solution). Combine various half-cells into pairs (galvanic cells) and try them out to power a stopwatch.
        Result: We identify the galvanic cells which provide enough voltage to power a stopwatch.

    Step 3

        Action: Combine various half-cells into pairs (galvanic cells) and measure the voltage of the various pairs of half-cells.
        Result: Create a series of electrode potentials arranged in order of the tendency of a metal ion to undergo reduction.

    Step 4

        Action: We measure voltage of a cell under standard conditions (1.0 M concentration). We change the concentration of one of the half-cells and observe the effect on the cell voltage. We repeat with various half-cell combinations.
        Result: We determine the values of cell voltage under non-standard conditions.

The following pages contain tutors to assist you with understanding and applying some concepts required in the above steps. Please click next to continue to the online activity.

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   Page Last Updated: 11.07.2016