Question

Among nickel (II) and platinum (II) compounds, which are more stable?

Answer 1

1. Nickel (II) compounds are more stable than platinum (II) compounds.
2. This is because the first and second ionisation enthalpies (energy required to form M²⁺) are lower for Ni (2.49 × 10³ kJ/mol) than for Pt (2.66 × 10³ kJ/mol).
3. Lower ionisation enthalpy means Ni(II) formation is easier and more thermodynamically stable compared to Pt(II).
4. However, Pt(IV) compounds are more stable than Ni(IV) because Pt’s total ionisation energy for +4 state is less.
5. Example: K₂PtCl₆ is well known, but the analogous Ni(IV) compound is not.