Electromotive Force : Basics

What does the double line mean?
Zn/Zn+2 // Cu+2/Cu

• anode
• cathode
• salt bridge
• substance in contact

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^-

Galvanic cells convert

• mechanical energy in to electrical energy

• potential energy in to electrical energy

• electrical energy in to chemical energy

• chemical energy in to electrical energy

Reference electrode that is universally used whose reduction potential value is zero is

• SHE

• Calomel electrode

• chlorine electrode

• standard zinc electrode

What is oxidation?

• It is the gain of electrons.

• It is the loss of electrons.

• It is the creation of electrons.

• It is the destruction of electrons.

What is reduction?

• It is the gain of electrons.

• It is the loss of electrons.

• It is the creation of electrons.

• It is the destruction of electrons.

What is a half-reaction?

• It is a reaction at equilibrium where half of the substances are reactants and half of the substances are products.

• It is the reaction that occurs when the switch of a galvanic cell is open.

• It shows EITHER the reduction component or the oxidation component of a redox reaction.

• It shows BOTH the reduction and oxidation components of a redox reaction.

What is a standard half-cell?

• It is one cell that comprises half of a whole battery.

• It is a cell containing only a metal bar with no aqueous ion solution.

• It is a cell containing only an aqueous ion solution and no metal bar.

• It is a cell that generates half of a volt of electricity.

Electrons always flow from

• cathode to anode

• anode to cathode

An iron nail is put into a solution of copper nitrate, iron is above copper in the activity series of metals, what will happen?

• iron will be reduced
• bubbles of oxygen gas will form on iron nail
• the iron nail will become copper plated
• no reaction occurs