31P Question: which of the following... [FREE SOLUTION]

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Chapter 13: 31P (page 599)

Question: which of the following compounds has a vibration that is infrared inactive.
1-butyne, 2-butyne, H₂, H₂O, Cl₂ and ethene

Short Answer

Expert verified

Answer

The compounds that are infrared active are 2-butyne, H₂, Cl₂ and ethene

Step by step solution

Factor for a compound to be infrared inactive

A compound is infrared active if it is symmetrical molecule. If the molecule is symmetrical then there is no dipole moment. Dipole moment is the reason for a molecule to be infrared active

1-butyne

1-butyne is asymmetrical about the C=C bond. There exists a very small change in dipole moment.So, the molecule is infrared active.

2-butyne

2-butyne is symmetrical about the C=C bond. There is no dipole moment. There will not occur stretching.so, the molecule is infrared inactive

Hydrogen molecule

Hydrogen molecule is symmetrical about H-H bond and no dipole moment possible.So, the molecule is infrared inactive.

Chlorine molecule

Chlorine molecule is symmetrical about Cl- Cl bond and has no dipole moment.So, the molecule is infrared inactive.

Step 6: Ethene

Ethene molecule is symmetrical about C=C bond. There is no dipole moment. So, there will not stretching to the molecule to be active.Hence, the molecule is infrared inactive.