Epsom salt (magnesium sulfate, MgSO4) is a neutral salt. When dissolved in water, it does not significantly alter the pH of the solution.

Here's why:

* Neutral salts are formed by the reaction of a strong acid and a strong base. Magnesium hydroxide (Mg(OH)2) is a strong base, and sulfuric acid (H2SO4) is a strong acid. When they react, they neutralize each other, forming the neutral salt magnesium sulfate.

* Neutral salts do not hydrolyze in water. Hydrolysis is the process where a salt reacts with water to form acidic or basic solutions. Since Epsom salt does not hydrolyze, it does not change the pH of the water.

Therefore, the pH of Epsom salt when mixed with water is approximately neutral (around 7).