Energy

Energy The capacity to do some kind of work. The capacity to do some kind of work. Involved when there is a change in matter Involved when there is a change in matter –Chemical –Physical

Endothermic “Within-Heating” Describes a process in which heat is absorbed from the environment. Describes a process in which heat is absorbed from the environment. Feels Cold Feels Cold Exothermic “Outside Heating” Describes a process in which heat is releases from the environment. Describes a process in which heat is releases from the environment. Feels Warm Feels Warm Examples Ice melting Water boiling Cold Pack Examples Freezing water Condensation Explosion

Law of Conservation of Energy The law that states that energy cannot be created or destroyed but can be changed from one form to another. The law that states that energy cannot be created or destroyed but can be changed from one form to another.

Heat The energy transferred between objects that are at different temperatures The energy transferred between objects that are at different temperatures Energy is always transferred from higher- temperature objects to lower-temperature objects until thermal equilibrium is reached. Energy is always transferred from higher- temperature objects to lower-temperature objects until thermal equilibrium is reached.

Kinetic Energy The energy of an object that is due to the object’s motion. The energy of an object that is due to the object’s motion. Potential Energy The energy stored within a physical system. The energy stored within a physical system.

Temperature A measure of the average kinetic energy of the particles in an object. A measure of the average kinetic energy of the particles in an object. A measure of how hot (or cold) something is. A measure of how hot (or cold) something is. Not dependent on the size or Not dependent on the size or type of object. Not energy Not energy Measurement of energy Measurement of energy

Temperature Scales Fahrenheit (not used in chemistry) Fahrenheit (not used in chemistry) Celsius Celsius –0°C Water Freezes –100°C Water Boils SI unit Kelvin SI unit Kelvin –Absolute zero (0 K)-minimum/zero average kinetic energy of all particles

Temperature Conversion t ( °C) = T (K) – K t ( °C) = T (K) – K T (K) = t ( °C) °C T (K) = t ( °C) °C Practice Practice  0 °C  50 K  120 °C  1000 K O °C = K 12O °C = K 50 K – K = °C 1000 K – K = °C

Transfer of Heat May not affect the temperature May not affect the temperature Phase Changes Phase Changes –Solid/Liquid –Liquid/Gas Affects Substances Differently Affects Substances Differently –Iron –Water Specific Heat Specific Heat –The quantity of heat required to raise a unit mass of homogeneous material 1 K or 1 °C in a specified way given constant pressure and volume.

Heating Curve for Water