# Voltaic cells concept questions and answers

1. What is a voltaic cell?

A voltaic cell is a type of electrochemical cell that generates electrical energy from spontaneous redox reactions taking place within the cell.

2. What is the difference between a voltaic cell and an electrolytic cell?

A voltaic cell converts chemical energy into electrical energy through a spontaneous redox reaction, whereas an electrolytic cell uses electrical energy to drive a non-spontaneous redox reaction.

3. What are the components of a voltaic cell?

A typical voltaic cell consists of two half-cells. Each half-cell contains an electrode and an electrolyte. The two half-cells are connected by a conductive wire and a salt bridge.

4. What happens at the anode and cathode in a voltaic cell?

In a voltaic cell, oxidation (loss of electrons) occurs at the anode and reduction (gain of electrons) occurs at the cathode.

5. What is the function of the salt bridge in a voltaic cell?

The salt bridge allows the flow of ions between the two half-cells, which maintains electrical neutrality throughout the cell.

6. What is a standard hydrogen electrode and why is it important?

The standard hydrogen electrode is a reference electrode which is assigned a potential of 0.00 volts. It is used to measure the standard electrode potentials of other electrodes.

7. Why is the anode considered negative in a voltaic cell?

The anode is considered negative in a voltaic cell because it is where oxidation takes place, meaning electrons are produced. These electrons are then pushed towards the cathode (positive terminal), creating an electric current.

8. What is the Nernst equation and how does it apply to a voltaic cell?

The Nernst equation is used to calculate the potential of a half-cell or full cell under non-standard conditions. It is given by E = E° – (RT/nF)lnQ, where E° is the standard cell potential, R is the gas constant, T is the temperature, n is the number of electrons, F is the Faraday constant, and Q is the reaction quotient.

9. What is the difference between primary and secondary voltaic cells?

Primary cells are those that cannot be recharged once the reactants are used up, while secondary cells can be recharged by reversing the flow of current to drive the reaction in the opposite direction.

10. Why is a voltmeter connected in a circuit containing a voltaic cell?

A voltmeter is used to measure the electric potential difference, also known as cell voltage, between the two electrodes in the voltaic cell.

1. What does it mean when we say a voltaic cell has “reached equilibrium”?

A voltaic cell has reached equilibrium when the cell potential has dropped to zero. This means the forward and reverse reaction rates are equal and no net change is occurring.

1. What happens in a voltaic cell when the concentrations of all species are equal?

When all species’ concentrations are equal, the cell potential (E) can be calculated using the Nernst equation, where the logarithmic term becomes zero and the potential equals the standard cell potential.

1. What is cell potential and how is it calculated in a voltaic cell?

The cell potential, also known as electromotive force (emf), is a measure of the potential difference between the two electrodes of a voltaic cell. It can be calculated using the formula E°cell = E°cathode – E°anode.

1. What are the energy changes in a voltaic cell?

In a voltaic cell, chemical energy is converted into electrical energy. The spontaneous redox reaction generates an electron flow, which can be used to do work.

1. What is a half-cell in the context of a voltaic cell?

A half-cell in a voltaic cell refers to one of the two parts of the cell where either oxidation or reduction occurs.

1. What is the role of electrons in a voltaic cell?

Electrons play a critical role in a voltaic cell. They are produced at the anode where oxidation occurs and are consumed at the cathode where reduction takes place. The movement of these electrons through a wire forms the basis of the electric current.

1. How does temperature affect the function of a voltaic cell?

An increase in temperature will generally increase the cell potential (voltage) of a voltaic cell. However, extreme temperatures may lead to faster degradation of the cell components, shortening the lifespan of the cell.

1. What is a real-world example of a voltaic cell?

A common example of a voltaic cell is a standard battery, such as a AA or AAA battery, which is used to power various electronic devices.

1. What would happen to a voltaic cell if the salt bridge was removed?

If the salt bridge was removed, the flow of ions between the half-cells would stop, disrupting the charge balance. This would cause the reaction to stop and the cell potential to fall to zero.

1. Why does a voltaic cell stop producing electricity after some time?

A voltaic cell stops producing electricity when it reaches equilibrium, which occurs when the reactants are depleted and the concentrations of products and reactants no longer change. At this point, the cell potential drops to zero.