Question

Carbon diselenide (CSe₂) is a liquid at room temperature. The normal boiling point is 125^oC and the melting point is -45.5^o . Carbon disulfide (CS₂) is also a liquid at room temperature, with normal boiling and melting points of 46.5^oC and -111.6^oC respectively. How do the strengths of the intermolecular forces vary from CO₂ to CS₂ to CSe₂? Explain your answer.

Short answer

The strength of intermolecular forces from CO₂ to CS₂ to CSe₂increases.

CO₂ < CS₂< CSe₂.

Step-by-step solution

Definitions of the vapor pressure, boiling point, and viscosity

Melting Point: The point at which compounds solid compounds transition into liquid compounds is known as the melting point.The melting point is directly proportional to the intermolecular forces of molecules.

Boiling point: The state at which compound changes from a liquid phase to a gaseous phase is known as the boiling point.The boiling point is directly proportional to the intermolecular forces of molecules.

Determine the strength of the intermolecular forces that vary from CO2 to CS2 to CSe2 .

The given compounds show the same structure. The size of molecules increases from CO₂ to CS₂ to CSe₂as moving down in the periodic table, the atomic size of atoms increases.The polarization and London dispersion forces are more in molecules having larger sizes. Therefore, the intermolecular forces are more in molecules having larger sizes, and the molecules have higher melting and boiling points.

The order of intermolecular forces: CO₂ < CS₂ < CSe₂.