Carbon diselenide \(\left(\mathrm{CSe}_{2}\right)\) is a liquid at room temperature. The normal boiling point is \(125^{\circ} \mathrm{C}\), and the melting point is \(-45.5^{\circ} \mathrm{C}\). Carbon disulfide \(\left(\mathrm{CS}_{2}\right)\) is also a liquid at room temperature with normal boiling and melting points of \(46.5^{\circ} \mathrm{C}\) and \(-111.6^{\circ} \mathrm{C}\), respectively. How do the strengths of the intermolecular forces vary from \(\mathrm{CO}_{2}\) to \(\mathrm{CS}_{2}\) to \(\mathrm{CSe}_{2}\) ? Explain.

: We will begin by listing the boiling and melting points of each substance: - Carbon dioxide (CO₂): Boiling point: -78.5°C, Melting point: -56.6°C - Carbon disulfide (CS₂): Boiling point: 46.5°C, Melting point: -111.6°C - Carbon diselenide (CSe₂): Boiling point: 125°C, Melting point: -45.5°C Please note that CO2 has a sublimation point at 1 atm pressure instead of boiling point due to its phase diagram. The given temperatures are approximations

: The boiling point can provide a good indication of the strength of the intermolecular forces in a substance. A higher boiling point implies stronger intermolecular forces, while a lower boiling point implies weaker intermolecular forces. Using the boiling points we listed in step 1, we can compare the substances as follows: CO₂ < CS₂ < CSe₂

: Melting points can also be used as an indicator of the strength of intermolecular forces within a substance. However, please note that it's not always perfectly correlated with boiling points. We can still compare the substances using their melting points: CO₂ < CSe₂ < CS₂

: From our comparison in steps 2 and 3, the boiling point trend of the substances is: CO₂ < CS₂ < CSe₂ This indicates that the intermolecular forces increase in strength from carbon dioxide to carbon disulfide to carbon diselenide. However, the melting points have slightly different trends: CO₂ < CSe₂ < CS₂ Considering both the boiling points and melting points, we can conclude that the strength of the intermolecular forces varies between these substances in the following way: CO₂ < CS₂ ≈ CSe₂ The intermolecular forces are weakest for carbon dioxide, stronger for carbon disulfide, and comparable in strength between carbon disulfide and carbon diselenide. This difference in strength can be attributed to the differences in molecular size and the presence of different types of electronegative atoms within the molecules. As the atom substitution changes (O to S to Se), the polarizability of the atoms increases leading to a higher London dispersion force between the molecules.