Sodium bromide (NaBr) dissolves in water because of the hydration energy released as a result of ion-dipole interactions formed between water and sodium and bromide ions. This hydration energy is greater than the lattice energy of sodium bromide. (Lattice energy is the energy required to break the lattice of NaBr).
NaBr is an ionic compound. When it is mixed with water, it dissolves readily. The solubility of this salt can be explained on the basis of the nature of the solute and solvent.
As we know “Like Dissolves like”. Both NaBr and water are polar compounds. So, they start interacting, as soon as they are placed together.
NaBr is highly polar. It turns into its constituent ions when added to water. Na+ attracts oxygen atom and Br– goes towards hydrogen atom in a water molecule. The new interactions that are being developed here are called hydrated bonds. The energy released during this process is called hydration energy. That energy is utilized to break the lattice.