Chapter 15 Quiz (electrochemistry)

What is the Nernst equation for

Mg(s) | Mg²⁺(aq, 0.001M) || Al³⁺(aq, 0.001 M) | Al (s)

• E_cell = E⁰_cell − 0.0592 / 6 log [Mg²⁺]³/ [Al³⁺]²

• E_cell = E⁰_cell − 0.0592 / 6 log [Al³⁺]²/ [Mg²⁺]²

• E_cell = E⁰_cell +0.0591 / 3 log[Mg²⁺]³/[Al³⁺]²

• E_cell = E⁰_cell −0.0591 / 3 log[Mg²⁺] /[Al³⁺]

Answer explanation

How could we increase the cell potential, E_cell based on this Nernst equation:

• Increase temperature

• Decrease concentration Ni²⁺

• Increase concentration Ni²⁺

• Choose E^ocell such that you obtain the highest negative value

Answer explanation

Increasing reactant concentration will decrease the Log value. Thus, E^o_cell will be subtracting a smaller value and E_cell value will be higher.

Given their standard reduction potentials, which of the species is going to be oxidized?

Cu²⁺/Cu = 0.34V

Zn²⁺/Zn = -0.76V

• Cu

• Zn

• CuSO4

• ZnSO4

What is a reducing agent?

• It is the species that gets reduced -- gains electrons.

• It is the species that gets oxidized -- loses electrons.

• It is the species that creates electrons.

• It is the species that destroys electrons.

In the following reaction

Sn⁺² + 2Fe⁺³ → Sn⁺⁴ + 2Fe⁺²

the oxidizing agent is....

• Sn⁺⁴

• Sn⁺²

• Fe⁺³

• Fe⁺²

Electrons always flow from

• cathode to anode

• anode to cathode

• Ni is being reduced

• Energy will be added to operate this cell.

• This cell operated spontaneously

What reaction occurs at the anode?

Ag⁺/Ag = 0.80V

Ni²⁺/Ni = -0.25V

• Ag⁺ + e^- →Ag

• Ag → Ag⁺ + e^-

• Ni²⁺ + 2e^- → Ni

• Ni → Ni²⁺ + 2e^-

Which will generally gain weight during electrolysis

• anode

• cathode

• salt bridge

• neither the anode or the cathode

How many moles of electrons are transferred in the reaction below?

2Al_(s) + 3Cu²⁺_(aq) → 2Al³⁺_(aq) + 3Cu_(s)

• 2

• 3

• 4

• 6