Electrochemical Cells Quiz

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Questions and Answers

What does the cell reaction in an electrochemical cell represent?

The reaction occurring exclusively at the anode
The sum of oxidation and reduction reactions (correct)
The decomposition of electrolyte solutions
The total number of electrons lost during oxidation

In the representation of a Galvanic cell, which part indicates the anode half-cell?

The entire cell reaction part
The region between the salt bridge
The part on the right side of the cell diagram
The part on the left side of the cell diagram (correct)

What is the significance of the double vertical lines (//) in a cell representation?

They indicate a potential difference between electrodes
They indicate the salt bridge between half-cells (correct)
They separate different phases of the same electrode
They represent a complete electrochemical cell

Which statement correctly describes the concept of electromotive force (EMF) in an electrochemical cell?

It is the potential difference required to drive electrons from the anode to the cathode (C) Signup and view all the answers

According to the Nernst equation, what does it relate?

Electrode potential to concentration of products and reactants (D) Signup and view all the answers

What does the zinc half-cell reaction represent in a Galvanic cell?

Oxidation by losing electrons (D) Signup and view all the answers

How is the EMF value of a cell typically represented?

By a numerical value written on the right side (A) Signup and view all the answers

What formula represents a general cell reaction for the Nernst equation?

aA + bB → cC + dD which includes temperature as a variable (D) Signup and view all the answers

What is the primary function of the salt bridge in an electrochemical cell?

To maintain electric neutrality in both half cells (C) Signup and view all the answers

Which type of electrode is typically used to measure the potential of another electrode?

Reference electrode (B) Signup and view all the answers

Which electrode is considered to have an electrode potential of 'zero' at all temperatures?

Standard Hydrogen Electrode (B) Signup and view all the answers

In a galvanic cell, what is the source of electrical energy?

Spontaneous redox reaction (B) Signup and view all the answers

Which of the following represents the reaction at the cathode in the given electrochemical cell?

Cu^2+ + 2e^- → Cu (B) Signup and view all the answers

Which of the following is NOT a type of electrode mentioned?

Primary electrode (D) Signup and view all the answers

Which equation is used to calculate the cell potential (EMF) of an electrochemical cell?

Ecell = E°cell - 0.0591/n log(Q) (C) Signup and view all the answers

What does 'n' in the Nernst equation represent?

Number of electrons involved in the cell reaction (D) Signup and view all the answers

What type of energy conversion takes place in a galvanic cell?

Chemical energy to electrical energy (C) Signup and view all the answers

In a galvanic cell, what is the charge of the anode?

Negative charge (D) Signup and view all the answers

Which of the following components is NOT part of a battery?

Reactor (B) Signup and view all the answers

What distinguishes a galvanic cell from an electrolytic cell?

The type of reaction occurring (D) Signup and view all the answers

What is a characteristic of galvanic cells?

They produce electricity spontaneously (D) Signup and view all the answers

What happens to the reactants in a primary battery after it is used?

They are consumed and cannot be reused (C) Signup and view all the answers

A lithium cell with a solid cathode is known as which type?

Lithium-MnO2 Cell (C) Signup and view all the answers

Which of the following is true about the voltage of a battery during discharge?

It should remain stable (A) Signup and view all the answers

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Study Notes

Electrochemical Cells

An electrochemical cell is a device that converts chemical energy into electrical energy or vice versa.
Consists of two half-cells: anode (oxidation) and cathode (reduction).
Cell reaction: Anode half-cell reaction + Cathode half-cell reaction.
Electrolyte: A solution that conducts electricity due to the movement of ions.
Salt bridge: A U-shaped tube filled with an electrolyte that connects the two half-cells, maintaining electrical neutrality.

Electromotive Force (EMF)

EMF or cell potential, is the potential difference required for electron flow from anode to cathode.
Determined by the difference in potential between the two half-cells and the nature of the electrolyte.

Cell Representation

Symbolic representation of a cell uses vertical lines (/) and double vertical lines (//) for phase boundaries and the salt bridge, respectively.
Left side: Anode half-cell.
Right side: Cathode half-cell.
Example: Zn/ZnSO4//CuSO4/Cu.

Nernst Equation

Relates electrode potential to concentration of reactants and products, and temperature.
Formula: Ecell = Eocell - (0.0591/n) * log (A^a B^b / C^c D^d)
Where:
- Ecell is cell potential.
- Eocell is standard cell potential.
- n is the number of electrons transferred.
- R is the gas constant.
- T is temperature.
- F is Faraday's constant.
- A, B, C, and D are the concentrations of the reactants and products.

Types of Electrochemical Cells

Galvanic cell (Voltaic cell): Converts chemical energy into electrical energy through spontaneous redox reactions.
Electrolytic cell: Converts electrical energy into chemical energy.

Reference Electrodes

Used to determine the electrode potential of another electrode.
Standard Hydrogen Electrode (SHE): Considered the primary reference electrode and has a potential of 0 Volts at all temperatures.
Standard Calomel Electrode (SCE): Another commonly used reference electrode.

Batteries

Collections of cells that store chemical energy and release it as electrical energy.
Main components: Anode, Cathode, and Electrolyte.
Characteristics:
- High capacity
- High energy efficiency
- Long shelf life
- Tolerance to different service conditions
- Affordable cost

Types of Batteries

Primary battery: Non-rechargeable, used only once.
- Examples: Lithium cells, Dry cells.
Secondary battery: Rechargeable, can be used for multiple cycles.
- Examples: Lead acid storage cells, Lithium-ion cells.

Lithium Cells

Primary cell: Uses Lithium (Li) as the anode.
Two types:
- Lithium Cell with Solid Cathode (LSC): Ex: Li-MnO2
- Lithium cell with Liquid Cathode (LLC): Ex: Li-SO2 and Li-SOCl2