When water freezes

When water freeze up phase change is occurred from liquid state to solid form. During the formation of ice, heat energy is released from water particles (K.E decreases). Hence it is an exothermic process.

$\text{Water}\left(l\right)\stackrel{\text{Freezing}}{\to }\text{\hspace{0.17em}Ice}\left(\text{s}\right)+\text{Energy}$