Problem 27 - Chemistry: The Central Science in SI Units, Global Edition

Question

Indicate whether each statement is true or false: (a) The cathode is the electrode at which oxidation takes place. (b) A galvanic cell is another name for a voltaic cell. (c) Electrons flow spontaneously from anode to cathode in a voltaic cell.

Step-by-Step Solution

Answer

(a) False - The cathode is the electrode at which reduction takes place. (b) True - A galvanic cell is another name for a voltaic cell. (c) True - Electrons flow spontaneously from anode to cathode in a voltaic cell.

Step 1: Statement (a)#

The cathode is the electrode at which oxidation takes place. This statement is false. In electrochemical cells, the cathode is the electrode where reduction takes place, while the anode is the electrode where oxidation takes place.

Step 2: Statement (b)#

A galvanic cell is another name for a voltaic cell. This statement is true. Galvanic cells and voltaic cells are two names for the same thing. They are electrochemical cells in which a spontaneous redox reaction generates electric current. In these cells, the anode is the site of oxidation, and the cathode is the site of reduction.

Step 3: Statement (c)#

Electrons flow spontaneously from anode to cathode in a voltaic cell. This statement is true. In a voltaic (galvanic) cell, the anode is the site of oxidation, meaning that it is losing electrons. These electrons flow through the external circuit to the cathode, which is the site of reduction and where these electrons are gained. This flow of electrons from anode to cathode generates an electric current.

Key Concepts

Cathode and Anode

In the world of electrochemical cells, understanding the roles of the cathode and the anode is crucial. These two electrodes are core components where essential reactions take place.

The **cathode** is the electrode where reduction occurs. This means that it is the site where electrons are gained during the cell's operation. Think of it as the 'electron receiver'. On the other hand, the **anode** is where oxidation takes place, making it the 'electron donor'. Electrons are lost by substances at the anode.

It's important not to get confused: oxidation occurs at the anode, and reduction happens at the cathode. Here are some tips to remember this:

• Anode: "A" comes first, like the beginning of the electron journey (oxidation).
• Cathode: "C" comes after "A", receiving electrons towards the end of their journey (reduction).

This distinction is key to predicting the flow of electrons in electrochemical reactions.

Voltaic/Galvanic Cells

Voltaic or galvanic cells are names that are often used interchangeably in chemistry. They describe a type of electrochemical cell where a spontaneous redox reaction generates an electric current. It's like creating a small power plant!

In these cells, chemical energy is converted into electrical energy through a clever arrangement of the anode and cathode in separate compartments, linked by a salt bridge or porous partition. This setup allows ions to flow between the compartments while keeping the solutions separate.

Here's how galvanic cells work:

• The anode undergoes oxidation and releases electrons.
• The cathode undergoes reduction, gaining the electrons that flowed from the anode.
• To balance the electron loss and gain, the ions in the salt bridge move to neutralize charge differences.

This flow of electrons from anode to cathode via an external circuit creates the electric current we harness in batteries and other devices. These cells are key components in our everyday technology, from simple batteries to complex systems.

Redox Reactions

Redox reactions, short for reduction-oxidation reactions, are a core part of electrochemistry. These reactions involve the transfer of electrons between substances, leading to changes in oxidation states. Understanding them is vital for grasping how electrochemical cells operate.

In a redox reaction, one substance loses electrons and is oxidized, while another gains electrons and is reduced.

Here's a quick breakdown of key concepts:

• Oxidation: Loss of electrons. Remember it as "OIL" (Oxidation Is Loss).
• Reduction: Gain of electrons. Think "RIG" (Reduction Is Gain).

These reactions are responsible for the flow of electrons in electrochemical cells, enabling the conversion from chemical energy to electrical energy. By understanding which parts of the reaction are oxidation and reduction, one can determine how electrodes in voltaic/galvanic cells operate and how devices powered by these cells function.