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Hydrolysis , type of chemical reaction in which a molecule of water , formula HOH, reacts with a molecule of a substance AB, in which A and B represent either atoms or groups of atoms. In the reaction the water molecule breaks into the fragments H + and OH - ; and the molecule AB breaks into A + and B - ; the fragments then join to give the final products AOH and HB. This kind of reaction is called a double decomposition or an exchange.

.. Changes in Matter is an alteration in the form or composition of matter. In science, matter is defined as anything that occupies space and possesses the attributes of gravity and inertia. Matter occurs in three forms: solid, liquid, or gas. Changes in matter may be of two types: physical or chemical. See also States of Matter PHYSICAL CHANGES A physical change is a change in matter that involves no chemical reaction. When a substance undergoes a physical change, the composition of its molecules remains unchanged, and the substance does not lose its chemical identity. Melting, evaporating, and freezing are three types of physical change. For example, water is a liquid that freezes to form the solid ice, which may again be melted into water. Because molecules of water and ice are composed of the same chemical elements in the same proportions, the change from water to ice is a physical change. Physical changes include any alteration in the shape and size of a substance. For example ...