Problem 42 - Chemistry The Central Science

Question

Determine if each statement is true or false: (a) Substitutional alloys are solid solutions, but interstitial alloys are heterogenous alloys. (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. (c) The atomic radii of the atoms in a substitutional alloy are similar to each other, but in an interstitial alloy, the interstitial atoms are a lot smaller than the host lattice atoms.

Step-by-Step Solution

Answer

(a) False: Both substitutional and interstitial alloys are solid solutions. (b) True: Substitutional alloys have solute atoms that replace solvent atoms in the lattice, while interstitial alloys have solute atoms in the interstitial spaces between solvent atoms. (c) True: In substitutional alloys, atomic radii of atoms are similar, while in interstitial alloys, interstitial atoms are smaller than host lattice atoms.

Step 1: Statement (a) Analysis

A substitutional alloy is a type of solid solution where the solute atoms replace the solvent atoms in a lattice. An interstitial alloy, on the other hand, has solute atoms that occupy the spaces between the solvent atoms in the lattice. The classification of alloys as either solid solution or heterogeneous is essential for determining whether the statement is true or false.

Step 2: Statement (a) Conclusion

The statement is false. Both substitutional and interstitial alloys are solid solutions. The difference between them lies in how the solute atoms interact with the solvent atoms' lattice and not in their classification as solid solutions or heterogeneous alloys.

Step 3: Statement (b) Analysis

We need to examine the distribution of solute atoms in substitutional and interstitial alloys. A substitutional alloy forms when the solute atoms replace the solvent atoms in a lattice, whereas interstitial alloys form as the solute atoms occupying the interstitial spaces between solvent atoms in the lattice.

Step 4: Statement (b) Conclusion

The statement is true. Substitutional alloys have "solute" atoms that replace the "solvent" atoms in the lattice, whereas interstitial alloys have "solute" atoms that reside in the interstitial spaces between the "solvent" atoms in the lattice.

Step 5: Statement (c) Analysis

For this statement, we need to compare the atomic radii of the atoms in substitutional and interstitial alloys. The atomic radii of atoms in a substitutional alloy are similar to each other, as they can replace each other in a lattice. In contrast, interstitial alloys have smaller interstitial atoms than the host lattice atoms.

Step 6: Statement (c) Conclusion

The statement is true. The atomic radii of the atoms in a substitutional alloy are similar to each other, allowing the solute and solvent atoms to replace each other in the lattice. In an interstitial alloy, the interstitial atoms are relatively small compared to the host lattice atoms, which enables them to fit in the spaces between the lattice atoms.