Question:

Correct order of dissociation energy of  \(N_2\) and \(N_2^+\) is:

Updated On: Oct 14, 2023
  • \(N_2>N_2^+\)

  • \(N_2=N_2^+\)

  • \(N_2^+>N_2\)

  • \(None\)

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The Correct Option is A

Solution and Explanation

The order of dissociation energy between \(N_2\) and \(N_2^+\) can be explained based on molecular and electronic structure.

N2 (Nitrogen Molecule):

  • \(N_2\) is a stable diatomic molecule with a triple bond between two nitrogen atoms \((N≡N)\).
  • In the \(N_2\) molecule, there is a strong triple bond holding the two nitrogen atoms together.
  • Breaking this bond to dissociate \(N_2\) into two nitrogen atoms requires a significant amount of energy. This is because the bond is strong and stable.
  • As a result, the dissociation energy of \(N_2\) is relatively high.

N2+ (Nitrogen Cation):

  • \(N_2^+\) refers to a nitrogen cation where one of the nitrogen atoms has lost an electron, leaving it with a positive charge.
  • In \(N_2^+\), the positive charge destabilizes the molecule compared to \(N_2\) because there are fewer electrons available for bonding.
  • The N-N bond in \(N_2^+\) is weaker than the \(N-N\) triple bond in \(N_2\) because it has lost one of its electrons.
  • Due to the weaker bond in \(N_2^+\), less energy is required to dissociate it into two nitrogen atoms.

In summary, \(N_2\) has a stronger and more stable triple bond, which means that it requires more energy to dissociate into its constituent nitrogen atoms. \(N_2^+\), on the other hand, has a weaker bond due to the loss of an electron, so it requires less energy for dissociation.

Therefore, the correct order of dissociation energy is option (A) \(N_2 > N_2^+\)

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Concepts Used:

Chemical Bonding and Molecular Structure

Such a group of atoms is called a molecule. Obviously, there must be some force that holds these constituent atoms together in the molecules. The attractive force which holds various constituents (atoms, ions, etc.) together in different chemical species is called a chemical bond.

Types of Chemical Bonds:

There are 4 types of chemical bonds which are formed by atoms or molecules to yield compounds. 

  • Ionic Bonds - Ionic bonding is a type of chemical bonding which involves a transfer of electrons from one atom or molecule to another.
  • Covalent Bonds - Compounds that contain carbon commonly exhibit this type of chemical bonding. 
  • Hydrogen Bonds -  It is a type of polar covalent bonding between oxygen and hydrogen wherein the hydrogen develops a partial positive charge
  • Polar Bonds - In Polar Covalent chemical bonding, electrons are shared unequally since the more electronegative atom pulls the electron pair closer to itself and away from the less electronegative atom.

Factors Affecting Bond Enthalpy in Chemical Bonding:

  • Size of the Atom
  • Multiplicity of Bonds
  • Number of Lone Pair of Electrons Present
  • Bond Angle