Question

A voltaic cell is constructed with two silver-silver chloride electrodes, each of which is based on the following half-reaction:

AgCl(s)+e−→Ag(s)+Cl−(aq).
The two cell compartments have [Cl−]=1.42×10−2 M and [Cl−]= 2.00 M , respectively.

Part A

Which electrode is the cathode of the cell?

the compartment with 1.42×10−2 M Cl(aq) is the cathode
the compartment with 2.00 M Cl(aq) is the cathode

Part B

What is the standard emf of the cell?

Part C

What is the cell emf for the concentrations given?

Part D

For the anode compartment, predict whether will increase, decrease, or stay the same as the cell operates.

increase
decrease
stay the same
Part E

For the cathode compartment, predict whether will increase, decrease, or stay the same as the cell operates.

increase
decrease
stay the same

Answer 1

Answer:

Part A

the compartment with 1.42×10−2 M Cl(aq) is the cathode

Part B

The standard emf of the cell is the  concentration of 1 M in an ideal solution is defined as the standard condition, and 1.100 V is thus the standard electromotive force.  

Part C

1.9858V

Part D

increase

Part E

decrease

Explanation:

1.

AgCl(s)+e−→Ag(s)+Cl−(aq).

In electrochemical cell, it is important to note that oxidation always occurs at the anode and reduction always occurs at the cathode.  

Also, electrons always flows from anode to cathode. In electrochemical cell, the negative electrode is the anode while the positive electrode is the cathode.

In the half equation:  

AgCl(s)+e− (reduction occurs), i.e cathode ; and

Ag(s)+Cl−(aq) (oxidation occurs) i.e anode.

2.

The standard emf of the cell is the  concentration of 1 M in an ideal solution is defined as the standard condition, and 1.100 V is thus the standard electromotive force.  

The maximum potential difference of the cell is known as the Electromotive force or e.m.f and it occurs when no current is flowing. It depends on some factors such as; concentrations of ions in the solution, the temperature at which the measurement is made and the overall energy change.

3.

When two half-cells are joined together, the e.m.f of the cell formed is the algebraic difference between the two electrode potentials. Hence, the e.m.f of the cell (E$^{0}$ total) formed by the system , AgCl(s)+e−→Ag(s)+Cl−(aq) is defined as the standard electrode potential of the right-hand electrode, minus the standard electrode potential of the left-hand electrode.

E$^{0}$ = E(r.h.e) – E(l.h.e)

      = 2.00 – (1.42 × 10$^{-2}$)

      = 2.00 – 1.42* 0.01

      = 2.00 – 0.0142

      = 1.9858V

4. at the anode, the chlorine undergo oxidation (increases) and lose one electron to form chlorine ion which goes into the solution. The chlorine  becomes negatively charged and functions as the anode.

5.

at the cathode silverchloride (Agcl) accepts the electrons to become reduced (decreased) to silver (ag$_{s}$) silver  gas and $cl^{-}_{aq}$ aqueous chloride ion.