Changes of State Chapter 3 Section 3

Changing States Caused By: removing or adding thermal energy a substance can lose or absorb thermal energy its temperature changes the speed of its particles changes and the state changes

Temperature Not all particles in a sample of matter have the same amount of energy Temperature: the average kinetic energy of particles in a substance (more kinetic energy = higher temp.) Example --->

Thermal Energy & Heat Thermal Energy Heat Is the total energy of the particles in a substance Heat movement of thermal energy from a warmer substance to cooler one (always w → c) heating → ↑ thermal energy ↑ motion of particles ↑ temp

Changing Energy Adding Energy Removing Energy endothermic – a reaction in matter in which energy is absorbed (melting is endothermic) temperature increases exothermic - a reaction in matter in which energy is released (freezing is endothermic) temperature decreases

Changes of State Melting Freezing freezing: change from a liquid to a solid freezing point: the temp. where a substance changes from liquid to solid melting: change from a solid to a liquid melting point: the temp. where a substance changes from solid to liquid Freezing & melting points of a substance are the same [ex. freezing & melting point of water is 32 ̊F or 0 ̊C]

Changes of State Vaporization Condensation vaporization: change from a liquid to a gas 2 Types: boiling: occurs below a liquid’s surface boiling point: the temp. where a substance begins to boil evaporation: occurs at a liquid’s surface condensation: change from a gas to a liquid

Changes of State Sublimation Deposition sublimation - change from a solid directly into a gas deposition: change from a gas directly into a solid

Changes of State

Changes of State