Problem 18 - Chemistry: The Central Science

Question

Which type of magnetic material cannot be used to make permanent magnets, a ferromagnetic substance, an antiferromagnetic substance, or a ferrimagnetic substance?

Step-by-Step Solution

Answer

Antiferromagnetic substances cannot be used to make permanent magnets because they do not exhibit spontaneous magnetization and have a net magnetization of zero when no external magnetic field is applied.

Step 1: Understand Ferromagnetic Substances

Ferromagnetic substances have a very high magnetization when subjected to a magnetic field, and they maintain their magnetization even after the magnetic field is removed. This property makes them suitable for making permanent magnets. Some examples of ferromagnetic materials include iron, cobalt, and nickel.

Step 2: Understand Antiferromagnetic Substances

Antiferromagnetic substances have magnetic moments that are oriented in opposite directions to their neighboring magnetic moments, which results in a net magnetization of zero when no external magnetic field is applied. This means that antiferromagnetic materials do not spontaneously magnetize and cannot be used to make permanent magnets. Examples of antiferromagnetic materials include manganese oxide and chromium.

Step 3: Understand Ferrimagnetic Substances

Ferrimagnetic substances have magnetic moments that are oriented in opposite directions, similar to antiferromagnetic substances. However, in ferrimagnetic materials, the magnitudes of the opposing magnetic moments are not equal, leading to a net magnetization in the absence of an external magnetic field. This property allows ferrimagnetic materials to be used in making permanent magnets. Examples of ferrimagnetic materials include magnetite and some ferrites.

Step 4: Identify the Material That Cannot Be Used for Permanent Magnets

Based on the properties of the three types of magnetic materials, we can conclude that antiferromagnetic substances cannot be used to make permanent magnets because they do not exhibit spontaneous magnetization and have a net magnetization of zero when no external magnetic field is applied.