No, adding salt to water is not an exothermic reaction that causes the temperature of the water to increase. Dissolving salt in water is actually an exothermic process, which means it releases heat. However, the overall temperature change of the water may not be significant or noticeable.
When salt (sodium chloride, NaCl) is added to water, the water molecules surround the individual ions of the salt, causing the salt to dissociate into its constituent ions (Na+ and Cl-). This process, known as hydration or dissolution, involves breaking the ionic bonds between the sodium and chloride ions and forming new bonds between the ions and water molecules.
The formation of these new bonds releases energy in the form of heat, making the process exothermic. However, the amount of heat released during the dissolution of salt is relatively small compared to the heat capacity of the water, so the change in temperature is usually negligible.
In summary, while adding salt to water is an exothermic process, it generally does not cause a noticeable increase in the temperature of the water.