Dry ice (solid CO2) is which type of solid?
A .nonbonding atomic solid
B. Atomic solid
C. lonic solid
D. molecular solid
The Correct Answer and Explanation is :
The correct answer is D. Molecular solid.
Dry ice (solid carbon dioxide, CO₂) is a molecular solid. Molecular solids are composed of molecules that are held together by relatively weak intermolecular forces such as Van der Waals forces, hydrogen bonds, or dipole-dipole interactions, rather than by covalent or ionic bonds. In the case of dry ice, the solid structure is composed of CO₂ molecules held together by Van der Waals forces.
Here’s an explanation of why dry ice is classified as a molecular solid:
Structure of Dry Ice:
Dry ice is made up of carbon dioxide molecules (CO₂). In the solid state, these molecules form a crystalline structure, where each CO₂ molecule interacts with adjacent molecules through weak Van der Waals forces. Unlike ionic solids (where atoms are held together by ionic bonds between positively and negatively charged ions) or covalent solids (where atoms are connected by strong covalent bonds), the forces between CO₂ molecules in dry ice are relatively weak. This is characteristic of molecular solids.
Properties of Molecular Solids:
- Low Melting and Boiling Points: Molecular solids tend to have lower melting and boiling points compared to ionic or covalent solids because the intermolecular forces are much weaker than ionic or covalent bonds. Dry ice sublimes directly from solid to gas at -78.5°C (−109.3°F), bypassing the liquid phase.
- Brittleness: Like many molecular solids, dry ice is brittle. When struck, it shatters into small pieces rather than deforming, similar to how many molecular solids behave.
- Lack of Electrical Conductivity: Molecular solids generally do not conduct electricity because they do not contain free-moving charged particles like ionic solids do.
Conclusion:
Thus, dry ice is a molecular solid because its structure is held together by weak intermolecular forces, and its components, CO₂ molecules, interact in this way, which is characteristic of molecular solids.