Mixing sodium chloride and water results in the formation of a homogeneous solution, which is a physical change. During this process, there is no chemical reaction between the two substances, and the chemical composition of both the sodium chloride and the water remains the same. The sodium chloride molecules disperse and become evenly distributed throughout the water, forming a uniform mixture at the molecular level. This process is reversible, meaning that the sodium chloride can be separated from the water by physical means, such as evaporation, to obtain the original substances in their unchanged chemical forms.