Ch.12 - Solids and Modern Materials

Problem 42b

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Chapter 12, Problem 42b

Determine if each statement is true or false: (b) Substitutional alloys have 'solute' atoms that replace 'solvent' atoms in a lattice, but interstitial alloys have 'solute' atoms that are in between the 'solvent' atoms in a lattice.

Verified step by step guidance

Understand the definition of substitutional alloys: In substitutional alloys, solute atoms replace solvent atoms in the lattice structure. This occurs when the solute and solvent atoms are of similar size.

Understand the definition of interstitial alloys: In interstitial alloys, smaller solute atoms fit into the spaces (interstices) between the larger solvent atoms in the lattice.

Compare the given statement with the definitions: The statement describes substitutional alloys as having solute atoms that replace solvent atoms, which matches the definition.

The statement also describes interstitial alloys as having solute atoms that fit between solvent atoms, which matches the definition.

Conclude that the statement is true based on the accurate descriptions of both substitutional and interstitial alloys.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Substitutional Alloys

Substitutional alloys are formed when solute atoms replace solvent atoms in the crystal lattice of a metal. This occurs when the solute and solvent atoms are of similar sizes and chemical properties, allowing for a uniform distribution within the lattice. An example is brass, where zinc atoms substitute for some copper atoms.

Interstitial Alloys

Interstitial alloys are created when smaller solute atoms occupy the spaces (interstices) between the larger solvent atoms in a metal lattice. This type of alloy typically enhances the strength and hardness of the base metal. A common example is steel, where carbon atoms fit into the interstitial spaces of iron.

Lattice Structure

The lattice structure refers to the organized, repeating arrangement of atoms in a solid material. In alloys, the lattice structure is crucial for determining the properties of the material, such as strength and conductivity. Understanding how solute and solvent atoms interact within this structure is essential for predicting the behavior of different alloy types.

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Lattice Energy

Related Practice

Aluminum metal crystallizes in a face-centered cubic unit cell. (a) How many aluminum atoms are in a unit cell? (b) Estimate the length of the unit cell edge, a, from the atomic radius of aluminum (1.43 Å). (c) Calculate the density of aluminum metal.

Textbook Question

An element crystallizes in a face-centered cubic lattice. The edge of the unit cell is 4.078 Å, and the density of the crystal is 19.30 g>cm3. Calculate the atomic weight of the element and identify the element.

Which of these statements about alloys and intermetallic compounds is false? (a) Bronze is an example of an alloy. (b) 'Alloy' is just another word for 'a chemical compound of fixed composition that is made of two or more metals.' (c) Intermetallics are compounds of two or more metals that have a definite composition and are not considered alloys. (d) If you mix two metals together and, at the atomic level, they separate into two or more different compositional phases, you have created a heterogeneous alloy. (e) Alloys can be formed even if the atoms that comprise them are rather different in size.

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Textbook Question

For each of the following alloy compositions, indicate whether you would expect it to be a substitutional alloy, an interstitial alloy, or an intermetallic compound: (b) Fe0.60Ni0.40

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Open Question

For each of the following alloy compositions, indicate whether you would expect it to be a substitutional alloy, an interstitial alloy, or an intermetallic compound: (a) Cu₀.₆₆Zn₀.₃₄ (b) Ag₃Sn (c) Ti₀.₉₉O₀.₀₁.

Textbook Question

Indicate whether each statement is true or false: (c) Nonmetallic elements are never found in alloys.

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