Structures of BeCl2 in solid state, vapor phase, and at very high… — Solution | JEE Chemistry

MCQEasyJEE 2023Hybridisation

Structures of $\text{BeCl}_2$ in solid state, vapor phase, and at very high temperature respectively are:

Answer

Correct answer:A

Standard Method

Given: The question asks the structures of $\text{BeCl}_2$ in solid state, vapor phase, and at very high temperature.

Find: The correct order of structures in these three conditions.

From the provided information:

In the solid state, $\text{BeCl}_2$ exists as a polymeric structure.
In the vapor phase below $1200 \, \text{K}$ , it exists as a dimer, namely $\text{Be}_2\text{Cl}_4$ , with chlorine bridges.
At very high temperature above $1200 \, \text{K}$ , it breaks into monomeric linear units.

Therefore, the order is Polymeric, Dimeric, Monomeric.

The correct option is A.

Confusing the solid-state structure with the vapor-phase structure. This is incorrect because $\text{BeCl}_2$ is polymeric in solid state due to bridging chlorine atoms, but becomes dimeric in vapor phase. First identify the physical state before choosing the structure.
Assuming that the compound remains dimeric even at very high temperature. This is incorrect because heating further breaks the bridged species into monomeric units. Always check how increasing temperature changes association.
Memorizing only one form of $\text{BeCl}_2$ and applying it to all conditions. This is incorrect because the structure depends on state and temperature. Learn the sequence: polymeric (\rightarrow) dimeric (\rightarrow) monomeric as temperature increases.

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