Sodium chloride has a lattice crystalline structure which corresponds to skillful solubility in water and its brittleness. Lattice structures are readily soluble in water when the hydration energy released as a consequence of dissolution equals or becomes greater than the lattice free energy which keeps the ions together (undissociated).

The hydration energy for NaCl is almost equal to its lattice energy. So, the undissociated grade becomes less stable than the dissolved or dissociated form of NaCl. This becomes the thermodynamic parameter of why is NaCl soluble in water.

Lattice energy of NaCl crystals

Lattice energy is an interpretation of bond free energy in a chemical compound which can be explained as the corporeality of energy released when gaseous opposite ions combine to brand a lattice crystal. The same happens in the case of NaCl lattice.

Why does NaCl dissolve in water?

The sodium and chloride ions in gaseous forms combine with each other to form a NaCl crystal lattice structure.

Na+ (aq) + Cl– (aq) → NaCl(s)

ΔHlatt = -787.iii KJ/mol

Hydration energy of NaCl crystals

The concept of hydration energy rests entirely on charge density. The accuse density is the corporeality of accuse per unit book of an ion. The smaller the size of ions, the more volition be the charge density and hence, more volition exist the hydration free energy. The opposite goes for larger ions making the hydration energy of sodium exist -406 KJ/mol and chloride to be -378 KJ/mol making the whole hydration energy of NaCl, -784 KJ/mol.

NaCl(s) → Na+ (aq) + Cl– (aq)

ΔHhyd = -784 KJ/mol

The hydration energy of NaCl is almost equal to the lattice energy, making NaCl more stable in hydrolyzed form. As the principle, 'Entropy increase makes a system stable' suggests, the dissociated form of NaCl is thermodynamically more stable than solid class, making NaCl soluble in water.

Other parameters of dissolution

Another parameter of dissolution of NaCl in water is the solvation or spectatoring by water molecules. Na+ and Cl– ions are surrounded by h2o molecules having their opposite charged sides, facing the ions. These h2o molecules are chosen spectator ions. The number of water molecules surrounding each sodium or chloride ion is 6 in the instance of NaCl, which makes these ions stable in dissociated form. Information technology is these spectator ions that do not let the sodium and chloride ions go back together unless all of the solvent is evaporated.

Similar to NaCl, NaBr and other lattice structures also dissolves in water,

Why does NaBr deliquesce in water?

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