Metal Electrode Set

Introduction

What causes an electric current to flow? Use the electrodes provided in this metal electrode set to investigate various electrochemical cell configurations and their voltages.

Concepts

  • Reduction potentials
  • Electrochemistry

Background

The Metal Electrode Set inlcudes the following:

{12863_Background_Table_1}

Materials

Complementary metal solutions, 1 M
Potassium chloride solution, saturated, KCl
Alligator clips with connecting wires, 2
Beakers, 400-mL, 2
Glass wool
Metal Electrode Set*
U-shaped drying tube
Voltmeter with range of 0–3 Volts
*Materials included in kit.

Safety Precautions

This activity requires the use of hazardous components and/or has the potential for hazardous reactions. Copper(II) sulfate solution is moderately toxic by ingestion. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Please review current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Each of the electrodes may be rinsed in water and stored for future use. The zinc sulfate and copper(II) sulfate solutions may be disposed of down the drain according to Flinn Suggested Disposal Method #26b. Any additional solutions used should be reused or disposed of according to their proper Flinn Suggested Disposal Method.

Procedure

Note: The following outlines the procedure for setting up an electrochemical cell using zinc and copper electrodes. Electrodes and their complementary solutions may be mixed and matched to design additional electrochemical cells.

  1. Fill a 400-mL beaker about two-thirds full with 1 M zinc sulfate solution, ZnSO4.
  2. Fill a second 400-mL beaker about two-thirds full with 1 M copper(II) sulfate solution, CuSO4.
  3. Fill the U-shaped drying tube with the saturated potassium chloride solution. Plug both ends of the tube with glass wool. Invert the tube and place it so that each end is immersed in one of the 400-mL beakers prepared in steps 1 and 2 (see Figure 1).
{12863_Procedure_Figure_1}
  1. Immerse the zinc electrode in the zinc sulfate solution. Immerse the copper electrode in the copper(II) sulfate solution.
  2. Attach an alligator clip to each of the electrodes. Attach the free end of the alligator clip connected to the zinc electrode to the negative terminal on the voltmeter. Attach the free end of the alligator clip connected to the copper electrode to the positive terminal on the voltmeter.
  3. Turn on the voltmeter and read the voltage. This voltage is the net cell potential.
  4. Repeat steps 1–6 using different electrode combinations. In each case, immerse an electrode in its complementary solution. For example, immerse the aluminum electrode in an aluminum sulfate solution.

Correlation to Next Generation Science Standards (NGSS)†

Science & Engineering Practices

Analyzing and interpreting data
Constructing explanations and designing solutions
Using mathematics and computational thinking

Disciplinary Core Ideas

MS-PS1.A: Structure and Properties of Matter
MS-PS1.B: Chemical Reactions
MS-PS3.C: Relationship between Energy and Forces
HS-PS1.A: Structure and Properties of Matter
HS-PS3.A: Definitions of Energy
HS-PS3.B: Conservation of Energy and Energy Transfer
HS-PS3.D: Energy in Chemical Processes

Crosscutting Concepts

Cause and effect
Energy and matter
Systems and system models
Patterns
Structure and function

Performance Expectations

HS-PS1-1. Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
HS-PS3-1. Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.
HS-PS3-2. Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motion of particles (objects) and energy associated with the relative position of particles (objects).

Discussion

An electric current will flow between two electrodes in an electrochemical cell if there is a difference in electrical potential energy between the two electrodes. In other words, if the standard reduction potentials for the two electrodes are different, an electric current will flow.

In an electrochemical cell, the electrode where oxidation occurs is called the anode while the electrode where reduction occurs is called the cathode (see Figure 1 in the Procedure). Electrons flow from the anode to the cathode.

The difference in electrical potential energy between two electrodes can be measured by incorporating a voltmeter into the electrochemical cell circuit (see Figure 1). The voltmeter will give a positive reading when its positive terminal is connected to the cathode and its negative terminal is connected to the anode. It will give a negative reading if the connections are reversed. The sign of the voltmeter reading helps to tell which electrode is the cathode and which is the anode if that is not already known. The larger the difference between the standard reduction potential of the two electrodes, the larger the voltage produced. This difference in electrical potential energy measured by the voltmeter is called the net cell potential and is represented by E°net.

To calculate the net cell potential, the standard reduction potentials for each of the half reactions in the cell are added together. The net cell potential for the copper/zinc electrochemical cell described in this activity is calculated below. The calculated value for E°net and the measured value given by the voltmeter should be equivalent.

{12863_Discussion_Equation_1}

This table of standard reduction potentials can be used to calculate the net cell potentials for various combinations of the electrodes included with the metal electrode set. Note: For the corresponding oxidation half-reaction, the sign of the reduction potential, E°, must be reversed.
{12863_Discussion_Table_2}

Recommended Products

Item No. Description
AP4602 Metal Electrode Set
AP1117 U-Shaped Drying Tube, 100 mm

†Next Generation Science Standards and NGSS are registered trademarks of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of this product, and do not endorse it.