Interhalogen compounds and polyhalogen ions

What factor offsets this and results in the standard enthalpies of formation of CrF2 and CrF3 being of the same order of magnitude  

The large negative values of Af7/ (298K) for both compounds show that the compounds are stable with respect to their constituent elements. 

There are two negative terms that help to offset this Aea77 (F) and Aij,tticeF7 (CrF3). Note also that  

In a series XY in which the oxidation state of X increases, the X—Y bond enthalpy term decreases, e.g. for the Cl—F bonds in CIF, CIF3 and CIF5, they are 257, 172 and 153kJmor respectively. 

Compound Appearance Melting Boiling Af7/°(298K) / Dipole Bond distances 

ttice (CrF3,s) - A,atticeF (CrF2,s) = -3119kJmor and this term alone effectively cancels the extra energy of 

Afff (AgF2, s) and At (AgF, s)= 360 and -205kJmor. Calculate values of Aj ttice for oach compound. Comment on the results in the light of the fact that the values of Aflf for AgF2 and AgF are of the same order of magnitude. 

Values of AjaniceTT for Mnp2 and Mnp3 (both of which are stable with respect to their elements at 298 K) are —2780 and 6006 kJ mol The third ionizatimi energy of Mn is 3248 kJ mol. Comment on these data. 

Compound Appearance at 298 K Melting point / K Boiling point/K AfFT (298K) / kj moP Dipole moment for gas-phase molecule / D Bond distances in gas-phase molecules except for IF3 and l2Cl6/pm  

J Exists only in equilibrium with dissociation products 2BrCl Br2 + CI2. 

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