Question

Calculate the standard cell potential for each of the following electrochemical cells. Express your answer in volts using two decimal places.

Ni2+(aq)+Mg(s)→Ni(s)+Mg2+(aq)
Cd(s)+2H+(aq)→Cd2+(aq)+H2(g)
Cr2O72−(aq)+14H+(aq)+6I−(aq)→2Cr3+(aq)+7H2O(l)+3I2(s)

Answer 1

To calculate the standard cell potential, identify the reduction and oxidation half-reactions for each cell, refer to standard electrode potentials, and use the equation E° cell = E° cathode - E° anode. A positive E° cell indicates a spontaneous reaction under standard conditions.

Step-by-step explanation:

The student is asking to calculate the standard cell potential for various electrochemical cells and determine if the reactions are spontaneous under standard state conditions. The standard cell potential (E° cell) is calculated using the standard electrode potentials of the reduction and oxidation half-reactions. To find out if the reaction is spontaneous, we check if E° cell is positive. Spontaneous reactions have a positive E° cell because they release free energy.

Example Calculations

For the reaction Ni2+(aq) + Mg(s) → Ni(s) + Mg2+(aq), identify the oxidation and reduction half-reactions and use their standard electrode potentials (found in tables of standard potentials). The standard cell potential is calculated as:

E° cell = E° cathode - E° anode

If the value of E° cell is positive, the reaction is spontaneous under standard conditions. Using this approach for- each chemical reaction provided, the cell potentials can be computed accurately along with their spontaneity status.

Answer 2

The standard cell potential can be calculated by subtracting the reduction potential of the anode from the reduction potential of the cathode.

Step-by-step explanation:

The standard cell potential for each of the given electrochemical cells can be calculated using the standard electrode potentials of each half-reaction involved. The standard cell potential is determined by subtracting the reduction potential of the anode from the reduction potential of the cathode.

For the electrochemical cell Ni2+(aq) + Mg(s) → Ni(s) + Mg2+(aq), the reduction half-reaction is Ni2+(aq) + 2e- → Ni(s) with a standard reduction potential of -0.25 V, and the oxidation half-reaction is Mg(s) → Mg2+(aq) + 2e- with a standard reduction potential of -2.37 V. Therefore, the standard cell potential is (-0.25) - (-2.37) = +2.12 V.

Similarly, for the other two electrochemical cells, the standard cell potentials can be calculated by subtracting the reduction potential of the anode from the reduction potential of the cathode.