Why sodium hydroxide is much more water soluble than chloride?

Explanation

NaOH is much more soluble than NaCl . Enthalpy of a solution can be expressed as the sum of lattice enthalpy and enthalpy of hydration of a compound.
`DeltaH"solu"NaCl=+3.9 kJ//mol`
`DeltaH"solu"NaCl=-44.5 kJ//mol`
`DeltaH_(0)" Lattice enthalpy of "NaCl `
`=+787.1 kJ`
Hydration enthalpy `=-784.1kJ`
Therefore `DeltaH_("solu")=-784.1kJ`
`=+3.5kJ`
Dissolution of NaCl is accompanied by very small heat change so solubility fo NaCl is less than NaOH.