Problem: The later members of group VB form pentafluorides: PF5, AsF5, and SbF5. At a given temperature, one of these is a solid, one a liquid and one a gas. Specify which is which.A. PF5 is a gas; AsF5 is a liquid; and SbF5 is a solidB. PF5 is a liquid; AsF5 is a solid; and SbF5 is a gasC. PF5 is a solid; AsF5 is a gas; and SbF5 is a liquidD. PF5 is a solid; AsF5 is a liquid; and SbF5 is a gasE. PF5 is a liquid; AsF5 is a gas; and SbF5 is a solid

FREE Expert Solution

We are being asked to specify which among  PF5, AsF5, and SbF5 would exist as solid, liquid and gas at a given temperature.


Recall that there are several types of intermolecular forces (IMF):

1. Ion-dipole interaction – occurs between an ion and a polar covalent compound; strongest IMF
2. Hydrogen bonding – occurs in compounds where hydrogen is directly connected to an electronegative element such as N, O, or F; 2nd strongest IMF
3. Dipole-dipole interaction – occurs between two polar covalent compounds; 3rd strongest IMF
4. Dispersion forces – occurs in all compounds and is the primary IMF exhibited by nonpolar compounds; weakest IMF


Compounds with strong intermolecular forces are most likely to exist as solids and compounds with weak intermolecular forces are most likely to exist as gases.

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Problem Details

The later members of group VB form pentafluorides: PF5, AsF5, and SbF5. At a given temperature, one of these is a solid, one a liquid and one a gas. Specify which is which.

A. PF5 is a gas; AsF5 is a liquid; and SbF5 is a solid

B. PF5 is a liquid; AsF5 is a solid; and SbF5 is a gas

C. PF5 is a solid; AsF5 is a gas; and SbF5 is a liquid

D. PF5 is a solid; AsF5 is a liquid; and SbF5 is a gas

E. PF5 is a liquid; AsF5 is a gas; and SbF5 is a solid