L3-11 STATES OF MATTER AND CHANGES OF STATE Water and all other forms of matter can exist in three different physical states; solid, liquid or gas The kinetic energy increases within the particles as you go from solid to gas As a substance absorbs thermal energy, the particles will vibrate more (ie. increases in kinetic energy) and the attractions between the particles decreases eventually fusion will occur when the substance melts The temperature will hover at the melting point until all of the particles have melted or undergone fusion A similar process occurs at the boiling point where vaporization or evaporation occurs A heating or cooling curve shows the temperature changes that occur as thermal energy is being absorbed or released Note: the temperature will remain constant at the boiling or melting point because all of the thermal energy is being used to change the potential energy of the substance as it undergoes the change of state

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Latent Heat - The thermal energy that is absorbed or released during the change of state is known as the latent heat (Q) and is measured in joules (J) - There are two kinds of latent heat: 1. the latent heat of fusion - this is the amount of thermal energy needed to change a substance from a solid into a liquid or a liquid into a solid

2. the latent heat of vaporization - this is the amount of thermal energy needed to change a substance from a liquid into a gas or a gas into a liquid Different substance will need different amount of latent heat to accomplish these phase changes because it has different kinds of particles the specific latent heat (L) is the amount of thermal energy needed to change 1 kg of a