Question

Apply Suppose that you have a voltaic cell in which one half-cell is made up of a strip of tin immersed in a solution of tin (II) ions. a. How could you tell by measuring voltage whether the tin strip was acting as a cathode or an anode in the cell? b. How could you tell by simple observation whether the tin strip was acting as a cathode or an anode?

Short answer

To determine if the tin strip is acting as a cathode or an anode by measuring voltage, measure the cell's voltage and compare it with the standard electrode potential of the tin(II)/tin couple (-0.14 V). If the measured voltage is greater than -0.14 V, the tin strip is acting as a cathode (reduction); if less than -0.14 V, it's an anode (oxidation). By observing the half-cell, if there is a visible deposition of tin on the strip's surface, it is acting as a cathode. If the tin strip is dissolving, it is acting as an anode.

Step-by-step solution

a. Measuring voltage to determine if the tin strip is a cathode or an anode

In a voltaic cell, the cathode is the site of reduction (gain of electrons), while the anode is the site of oxidation (loss of electrons). By measuring the voltage of the cell, we can determine if the tin strip is acting as a cathode or an anode. 1. Measure and take note of the voltage of the cell. Before we proceed, we should first measure the voltage of the voltaic cell using a voltmeter. Take note of the voltage reading. 2. Compare the measured voltage with the standard electrode potential of the tin (II)/tin couple. The standard electrode potential of the tin (II)/tin couple is \( -0.14 V \) . If the measured voltage is greater than \( -0.14 V \), it indicates that the tin strip is acting as a cathode (the site of reduction). Conversely, if the measured voltage is less than \( -0.14 V \), it indicates that the tin strip is acting as an anode (the site of oxidation).

b. Observing the half-cell to determine if the tin strip is a cathode or an anode

In a voltaic cell, we can use simple observation to ascertain if the tin strip is acting as a cathode or an anode. Here are the signs to observe: 1. Look for deposition of tin on the strip's surface. If the tin strip is acting as a cathode, it will lead to the reduction of tin (II) ions in the solution to form solid tin. As a result, there will be a visible deposition of tin on the surface of the strip. If we see such deposition, the tin strip is acting as a cathode. 2. Watch for dissolution of the tin strip. If the tin strip is acting as an anode, it will undergo oxidation and will dissolve into the solution as tin (II) ions. If we observe that the tin strip is dissolving, it indicates that the strip is acting as an anode.

Key concepts

Electrode Potential

Electrode potential refers to the ability of an electrode to drive an electric current through a cell. In an electrochemical context, each half-cell has a potential, measured by the tendency of a metal to lose or gain electrons. The electrode potential is typically expressed in volts (V).

This potential can be positive or negative, depending on the nature of the material. A higher (more positive) standard electrode potential indicates a greater tendency for reduction, while a lower (more negative) value indicates a tendency for oxidation.

• Reduction potential refers to electrodes that tend to gain electrons easily.
• Oxidation potential applies to electrodes that tend to lose electrons easily.

In the case of the tin electrode, the standard electrode potential of the Tin(II)/Tin couple is \( -0.14 \, V \). To determine the role of the tin strip in the voltaic cell, you compare the actual cell voltage to this standard potential.

Oxidation-Reduction Reactions

Oxidation-reduction reactions, or redox reactions, are chemical reactions wherein electrons are transferred between atoms.

These reactions are a fundamental part of electrochemical cells. They involve two key processes: oxidation and reduction.

• Oxidation: This involves the loss of electrons. In a voltaic cell, the oxidation happens at the anode.
• Reduction: This involves the gain of electrons. Conversely, reduction occurs at the cathode.

In a voltaic cell where a tin electrode is involved, if the tin strip acts as the anode, it will undergo oxidation, dissolving into the solution as tin ions.

If the tin strip acts as the cathode, it will undergo reduction, leading to the deposition of tin on its surface. Observing these changes can help identify the electrode's role in the cell.

Tin Electrode

A tin electrode refers to a conductive strip made of tin used in electrochemical cells. This electrode participates in redox reactions, playing a crucial role in the cell's function.

The tin electrode can either act as a cathode or an anode, depending on its involvement in the chemical reaction.

• As a cathode, it undergoes reduction, where tin ions gain electrons and deposit new tin onto the strip.
• As an anode, it experiences oxidation, as tin atoms lose electrons and dissolve into the solution as ions.

By closely monitoring the tin electrode, you can determine the current direction and the specific reactions occurring in the cell. This information is essential for understanding cell performance.

Electrochemical Cell

An electrochemical cell is a device capable of converting chemical energy into electrical energy through redox reactions. They are composed of two half-cells, each having its electrode submerged in a solution of its ions.

In a typical voltaic cell, the electrodes are connected externally through a wire, allowing electrons to flow from the anode to the cathode.

• The anode is where oxidation occurs, releasing electrons into the circuit.
• The cathode is where reduction occurs, consuming electrons from the circuit.

Electrochemical cells are the basis of batteries and many other devices that power our daily lives. Identifying the roles of the electrodes, such as with the tin strip in this exercise, is crucial for understanding and optimizing the functionality of these cells.