Answered

  1. Compare and contrast an electrolytic cell with a voltaic cell.




Electrolytic Cell Differences		SimilaritiesVoltaic Cell Differences

Uses external power for nonspontaneous reactions ( ${ }^{\wedge} G		gt;0$ )\multirow{3}{*}{\begin{tabular}[t]{l}
Both involve redox reactions

Both have an anode (oxidation) and cathode (reduction)

Both use an electrolyte to conduct ions
} & Generates electricity from spontaneous reactions $\left({ }^{\wedge} G <0\right)$ \\

\hline Converts electrical energy to chemical energy & & Converts chemical energy to electrical energy \\

\hline Anode is positive; Cathode is negative & & Anode is negative; Cathode is positive \\

\hline

\end{tabular}


  1. Using the information from question #15, provide one example where both are present in daily life and explain how it is both voltaic and electrolytic.

Verified Answer :

  • Identify the rechargeable battery as a device that acts as both a voltaic and an electrolytic cell depending on whether it is discharging or charging.
  • Explain the voltaic phase (discharging): Spontaneous redox reactions convert stored chemical energy into electricity (\(\Delta G < 0\)), with the anode as negative and the cathode as positive.
  • Explain the electrolytic phase (charging): An external energy source forces non-spontaneous reactions to convert electricity back into chemical energy (\(\Delta G > 0\)), reversing the polarity of the electrodes.
  • Link both phases to the shared core components of redox processes and the presence of an anode, cathode, and electrolyte.

Explanation

  1. Identification of the Dual-Purpose Device

A rechargeable battery, such as a lithium-ion battery commonly found in smartphones, serves as an excellent real-world example that operates as both a voltaic cell and an electrolytic cell. These two modes of operation represent different phases of the battery's cycle: discharging and charging. To understand this dual nature, one must look at the spontaneity of the redox reactions and the direction of energy conversion occurring within the battery's components.

  1. Voltaic Operation (Discharging Phase)

When a battery powers a device, it functions as a voltaic cell. In this state, the chemical reactions are spontaneous, meaning the change in Gibbs free energy is negative (\(\Delta G < 0\)). The stored chemical energy is converted into electrical energy, which drives the current through the external circuit. During this phase, the anode is the negative electrode (where oxidation occurs), and the cathode is the positive electrode (where reduction occurs). This process powers the device by releasing electrons that flow from the anode to the cathode.

  1. Electrolytic Operation (Charging Phase)

When the battery is connected to an external power source (such as a charger), it functions as an electrolytic cell. In this state, the redox reactions are non-spontaneous (\(\Delta G > 0\)), requiring the input of electrical energy from the charger to drive the process in reverse. This energy is converted back into chemical potential energy, restoring the battery's charge. In this mode, the polarity shifts: the electrode that served as the anode during discharge now acts as the positive anode (where oxidation occurs), and the electrode that served as the cathode now acts as the negative cathode (where reduction occurs).

  1. Synthesis and Conclusion

Despite their differences in energy conversion and spontaneity, both operations share the fundamental characteristics of electrochemical cells. Both involve redox reactions, both utilize an anode and a cathode, and both require an electrolyte to facilitate the flow of ions between the electrodes. The rechargeable battery effectively manages these transitions, demonstrating how energy can be stored as chemical potential and released as electrical work, and subsequently restored using an external power source.

Examples

Consider your smartphone battery throughout a typical day. When you use your phone to send messages or watch videos, the battery is acting as a voltaic cell, spontaneously converting chemical energy into the electrical power required to operate the screen and processor. When you plug your phone into a wall charger at the end of the day, the charger acts as an external power source, forcing the battery to act as an electrolytic cell. It non-spontaneously drives current back into the battery, converting electrical energy from the outlet into chemical potential energy for future use. This cycle of discharging and charging is a perfect everyday manifestation of the interplay between voltaic and electrolytic processes.

Related Questions