Voltaic cells

Electrochemistry- salt, voltaic cells and oxidation-reduction

1. Why do cars rust quickly in cold climates where the roads are deiced by the spreading of salt? Choose from:

The combination of low temperature and the presence of ions makes the redox reaction for forming rust more favorable.
The salt acts as the cathode to complete the "cell."
The salt promotes the formation of hydronium ion, which increases the electrode potential of oxygen gas.
Salt solutions, because they produce ions, enhance current flow between the iron metal in the car body and the oxygen gas in air.

2. What is the fundamental difference between a voltaic cell and an electrolytic cell? Choose from:

A voltaic cell maintains the current within the cell, while an electrolytic cell draws the current off to perform a different chemical reaction.
A voltaic cell generates current from a spontaneous chemical reaction, while an electrolytic cell uses current to drive a chemical reaction.
A voltaic cell relies on redox reactions of metals, while an electrolytic cell is used to split water into hydrogen and oxygen.
A voltaic cell does not depend on the stoichiometry of redox reactions, but an electrolytic cell does.

3. Can a voltaic cell in which both half-reactions are the same generate a current?Choose from:

Yes, if there is a difference in concentration between the two half-reactions.
Yes, as long as the two are connected by a salt bridge, a current can flow.
No, if there is no difference in standard cell potential between the half-reactions, there can be no driving force for electrons to flow.
Yes, electrons always flow toward the electrode with the more positive standard reduction potential regardless of the identity of the half-reactions.

4. How are the equilibrium constant and the standard cell potential of an oxidation-reduction reaction related? Choose from:

Both are a function of the number of electrons transferred in the reaction.
They are not related. The equilibrium constant derives from enthalpy while reduction potential only deals with charge.
Both are a function of the standard change in Gibbs free energy.
Both are related to the amount of work that can be done by a reaction on its surroundings.

5. How can standard electrode potentials be used to gauge a half-reaction's tendency to gain electrons? Choose from:

The more negative the standard electrode potential, the greater is the tendency to participate in spontaneous reactions.
The individual standard electrode potentials do not indicate anything about tendency to gain electrons. The cell potential of the entire cell does.
The more positive the standard electrode potential, the greater the tendency to undergo reduction, thereby gaining electrons.
Standard electrode potentials are neither positive nor negative, since we define the standard hydrogen electrode as having a potential of zero.

6. Why does a galvanic cell have a salt bridge connecting the two half-cells? Choose from:

Ions in the salt bridge allow the electrons to move from one electrode to the other.
The salt bridge allows ions to flow to each half-cell to compensate for charge buildup at the electrodes.
Some electrodes are inert, so the salt bridge is necessary to allow the reaction to occur.
The salt bridge provides an additional source of ions to act as reactants or products.

View Full Posting Details