HINT: i. ii. iii. iv. V. The energy stored in a compound is called the energy content or the (1) of the compound. An (2) reaction is a reaction that (3) heat energy into its surroundings. In an (2) reaction, the enthalpy of the product is less than the enthalpy of the reactants. Hence, the enthalpy change of the reaction is (4). An (5) reaction is a reaction that (6) heat energy from its surroundings. In an (5) reaction, the enthalpy of the product is greater than the enthalpy of the reactants. Hence, the enthalpy change of the reaction is (7). The standard enthalpy of (8) of an element or a compound is the enthalpy change when 1.0 mole of the substance is completely burnt in (9) under the standard conditions of 298K and 1.0 atm. The standard enthalpy of (10) of a compound is the heat evolved or absorbed when 1.0 mole of the compound is formed from its elements in their normal physical states under the standard conditions of 298 K and 1.0 atm. The (11) cycles is a special case of (12) Law as applied to ionic compound. It is an energy cycle. (13) energy can be used to explain the melting points of ionic compounds and the presence of covalent character in some ionic compounds. The heat evolved or absorbed when 1.0 mole of solute dissolves in water to form an infinitely dilute solution is known as the standard enthalpy of (14). For example, NaCl (s) + water NaCl (aq) 4H, = 3.9kjmol The standard enthalpy of (15) of an element is the enthalpy change when one mole of gaseous atom is formed from the element in the standard state. The heat evolved when one mole of H* ions reacts with one mole of OH ions to form one mole of water molecules under standard conditions of 298K and 1 atm, is known as the standard enthalpy of (16). vi. vii. ix