Ammonium salts are chemical compounds formed when ammonia (NH3) reacts with an acid. They typically consist of the ammonium ion (NH4+) and an anion from the acid. Common examples include ammonium chloride (NH4Cl) and ammonium sulfate ((NH4)2SO4). These salts are often used in fertilizers, food additives, and various industrial applications. In solution, ammonium salts can dissociate into their constituent ions, contributing to the solution's acidity. They are generally soluble in water, making them useful in many chemical processes. Additionally, ammonium salts play a role in biological systems, such as in the nitrogen cycle, where they are important for plant nutrition.