Question

Two different compounds have the formula \(\mathrm{XeF}_{2} \mathrm{Cl}_{2} .\) Write Lewis structures for these two compounds, and describe how measurement of dipole moments might be used to distinguish between them.

Short answer

The two possible arrangements for \(\mathrm{XeF}_{2} \mathrm{Cl}_{2}\) have different shapes and dipole moments. Arrangement 1: \(\mathrm{Xe}( \mathrm{F})( \mathrm{F})( \mathrm{Cl})( \mathrm{Cl})\) is asymmetrical and has nonzero dipole moment, while arrangement 2: \(\mathrm{Xe}( \mathrm{F})( \mathrm{Cl})( \mathrm{F})( \mathrm{Cl})\) is symmetrical and has a zero dipole moment. By measuring the dipole moment, we can distinguish between the two compounds - a nonzero value indicates arrangement 1, while a zero value indicates arrangement 2.

Step-by-step solution

Identify possible arrangements of atoms for the given formula

Since we are given the formula \(\mathrm{XeF}_{2} \mathrm{Cl}_{2}\), we can predict two possible arrangements for the molecule: 1. Xe in the center, with two F atoms and two Cl atoms attached to it: \(\mathrm{Xe}( \mathrm{F})( \mathrm{F})( \mathrm{Cl})( \mathrm{Cl})\) 2. Xe in the center, with one F and one Cl atom on one side and one F and one Cl atom on the other side: \(\mathrm{Xe}( \mathrm{F})( \mathrm{Cl})( \mathrm{F})( \mathrm{Cl})\)

Draw the Lewis structures for the two possible arrangements

For both possible arrangements, draw the Lewis structures by following these steps: 1. Identify the valence electrons for each atom 2. Connect the atoms with single bonds and complete the octets with electron pairs 3. Check if the octet rule is followed For arrangement 1: 1. Xe - 8 valence electrons, F - 7 valence electrons, Cl - 7 valence electrons 2. Xe - F - F - Cl - Cl with single bonds and complete the octets with electron pairs 3. Octet rule is followed For arrangement 2: 1. Xe - 8 valence electrons, F - 7 valence electrons, Cl - 7 valence electrons 2. Xe - F - Cl - F - Cl with single bonds and complete the octets with electron pairs 3. Octet rule is followed

Determine the dipole moments of both arrangements

In order to determine the dipole moments of both arrangements, first identify the electronegativity difference between Xe, F, and Cl. - Xe: 2.6 - F: 3.98 - Cl: 3.16 Now, we can calculate the difference in electronegativities for the bonds: - Xe-F: 1.38 - Xe-Cl: 0.56 For arrangement 1: Since F and Cl are not identical, the structure is asymmetrical. Therefore, there will be a net dipole moment present. For arrangement 2: The molecule is symmetrical; hence, individual bond dipole moments will cancel each other out. Therefore, there will be no net dipole moment present for this arrangement.

Use the dipole moment measurements to distinguish the two compounds

Based on the results obtained in step 3, we can use the dipole moment measurements to distinguish between these two compounds. For both arrangements: 1. If the dipole moment measurement is nonzero, the compound corresponds to arrangement 1 - an asymmetrical structure with a net dipole moment present. 2. If the dipole moment measurement is zero, the compound corresponds to arrangement 2 - a symmetrical structure with no net dipole moment present.