Standard electrode potential

What is standard cell potential (E⁰cell)?

• The voltage of a cell under non-standard conditions.

• The voltage of a cell when reactants and products are at standard conditions.

• The voltage of a cell with a cell with reactants and products at any conditions.

• The voltage of a cell when no redox reaction is occurring?

Answer explanation

In short, "standard cell potential" (E° cell) is the electric potential generated by galvanic cell when when reactant and product are at standard conditions, serving as a measure of the cell's voltage. It helps the spontaneity and direction of redox direction.

Which of the following statements is true regarding standard cell potential (E°cell)?

• It depends on the concentrations of reactants and product

• It is an intensive property.

• It is only applicable to non-spontaneous reactions.

• It decreases as the temperature increases.

Answer explanation

An intensive property is a characteristic of a substance or a system that doesn't change with the amount of the substance or the size of the system. It's like a property that's specific to the substance itself and doesn't depend on how much of it you have. For example, think of the color of an object. Whether you have a small piece or a big piece of the same material, the color remains the same. Color is an intensive property because it doesn't change with the amount of the substance. In the context of standard cell potential (E°cell), it means that the E°cell value is unique to the specific chemical reaction and the substances involved. It doesn't matter if you have a little or a lot of those substances; the E°cell remains the same for that particular reaction. It's a fixed value under standard conditions and is independent of the amount of reactants or the size of the electrochemical cell.

In a galvanic cell, if the E°cell is positive, what can you conclude about the spontaneity of the redox reaction?

• The reaction is spontaneous.

• The reaction is non-spontaneous.

• The reaction's spontaneity cannot be determined from E°cell.

• The reaction is at equilibrium.

Answer explanation

If the E°cell (the number that tells us the cell's voltage) in a galvanic cell is positive, it means that the chemical reaction happening in the cell is a natural and "happy" reaction. It occurs on its own without needing any extra help. Think of it like a ball rolling downhill because of gravity. It naturally goes down the hill without anyone pushing it. In the same way, a positive E°cell means the reaction naturally happens, and you don't need to force it. It's a sign that the reaction is spontaneous and will occur without any external effort.

Which of the following equations represents the Nernst equation for calculating

the cell potential under non-standard conditions?

• Ecell = E°cell - (0.0592/n) * log(K)

• E°cell = Ecell - (0.0592/n) * log(Q)

• Ecell = E°cell - (0.0592/n) * log(Q)

• E°cell = Ecell - (0.0592/n) * log(K)

If the E°cell for a given cell is 0.74 V and the cell potential under non-standard conditions is

calculated to be 0.68 V, what can you infer about the reaction quotient (Q) for this cell?

• Q > 1

• Q < 1

• Q = 1

• Q is not related to E°cell or Ecell.

Which half-cell reaction occurs at the cathode in a galvanic cell?

• Oxidation

• Reduction

• Neither oxidation nor reduction

• Both oxidation and reduction

In the Daniell cell, which of the following half-reactions takes place at the anode?

• Zn(s) → Zn²⁺(aq) + 2e⁻

• Cu²⁺(aq) + 2e⁻ → Cu(s)
  

• 2H⁺(aq) + 2e⁻ → H₂(g)

• 2Cl⁻(aq) → Cl₂(g) + 2e⁻

If you want to calculate the cell potential of a redox reaction, and you know the standard reduction potentials (E°) of both half-reactions, how do you proceed?

• Divide the reduction potential of the anode half-reaction by the reduction potential of the cathode half-reaction.

• Subtract the reduction potential of the anode half-reaction from the reduction potential of the cathode half-reaction.

• Take the average of the reduction potentials of the two half-reactions.

• Subtract the reduction potential of the anode half-reaction from the reduction potential of the cathode half-reaction.

Which of the following options represents the formula for standard cell potential (E°cell)?

• Ecell = nF/RT * ln(Q)

• Ecell = RT/nF * ln(Q)

• E°cell = E°r (cathode) - E°r (anode)

• Ecell = ΔG°/nF

What happens to the standard cell potential (E°)

if you reverse the half-cell equation for the cathode in a redox reaction?

• E° remains the same.

• E° becomes zero.

• E° changes sign to the opposite.

• E° doubles.