---
title: "A student compares the physical properties of silicon dioxide, \\(\\text{SiO}_2\\text{(s)}\\), and carbon dioxide, \\(\\text{CO}_2\\text{(s)}\\). The student notes that \\(\\text{SiO}_2\\text{(s)}\\) has a melting point of \\(1710^\\circ\\text{C}\\), whereas \\(\\text{CO}_2\\text{(s)}\\) sublimes at \\(-78^\\circ\\text{C}\\) at atmospheric pressure. Which of the following statements best accounts for the large difference in phase-change temperatures between the two substances?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/119193/"
date_modified: "2026-08-19T12:39:17+00:00"
---

# A student compares the physical properties of silicon dioxide, \(\text{SiO}_2\text{(s)}\), and carbon dioxide, \(\text{CO}_2\text{(s)}\). The student notes that \(\text{SiO}_2\text{(s)}\) has a melting point of \(1710^\circ\text{C}\), whereas \(\text{CO}_2\text{(s)}\) sublimes at \(-78^\circ\text{C}\) at atmospheric pressure. Which of the following statements best accounts for the large difference in phase-change temperatures between the two substances?

A student compares the physical properties of silicon dioxide, \(\text{SiO}_2\text{(s)}\), and carbon dioxide, \(\text{CO}_2\text{(s)}\). The student notes that \(\text{SiO}_2\text{(s)}\) has a melting point of \(1710^\circ\text{C}\), whereas \(\text{CO}_2\text{(s)}\) sublimes at \(-78^\circ\text{C}\) at atmospheric pressure. Which of the following statements best accounts for the large difference in phase-change temperatures between the two substances?

- **A.** \(\text{SiO}_2\text{(s)}\) has a much higher melting point because phase change requires breaking strong covalent bonds within a continuous network lattice, whereas phase change of \(\text{CO}_2\text{(s)}\) requires overcoming much weaker intermolecular forces between discrete molecules.
- **B.** \(\text{SiO}_2\text{(s)}\) has a much higher melting point because melting \(\text{SiO}_2\text{(s)}\) breaks the strong \(\text{Si}-\text{O}\) covalent bonds within discrete \(\text{SiO}_2\) molecules, whereas melting \(\text{CO}_2\text{(s)}\) breaks the weaker \(\text{C}=\text{O}\) double bonds within discrete \(\text{CO}_2\) molecules.
- **C.** \(\text{CO}_2\text{(s)}\) has a much lower sublimation temperature because the polar \(\text{C}=\text{O}\) bonds create repulsive forces between adjacent \(\text{CO}_2\) molecules, whereas nonpolar \(\text{Si}-\text{O}\) bonds in \(\text{SiO}_2\) attract each other.
- **D.** \(\text{CO}_2\text{(s)}\) has a much lower sublimation temperature because phase change requires breaking covalent bonds in \(\text{CO}_2\text{(s)}\), whereas phase change of \(\text{SiO}_2\text{(s)}\) requires overcoming only London dispersion forces.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119193/*