Transcript Document
2-1 What is Energy CHEMICAL ENERGY The energy that matter possesses because of its chemical makeup Comps. have chem. energy bec. of the atoms they contain and the bonds that hold them together CHEMICAL BOND – a mutual attraction betw. diff. atoms that binds the atoms together KINETIC ENERGY Energy a moving object has bec. of its motion Atoms & molecs. are in constant motion POTENTIAL ENERGY energy an object has bec. of its position position of atoms • When positions change, bonds are formed or broken & energy is absorbed or released rxns. change positions of atoms and potential energy changes All chemical & physical changes involve a change in energy. freezing evaporating dissolving explosion burning ENERGY the capacity to do work LAW OF CONSERVATION OF ENERGY in any chemical or physical process, energy is neither created nor destroyed total amt. of energy in the universe is constant energy just changes form Energy can be transferred. HEAT the sum total of kinetic energy of the particles in a sample of matter can be transferred due to a difference in temp. SYSTEM a specific portion of matter in a given region of space that has been selected for study during an experiment or observation. complex or simple everything outside system is surroundings Heat transfer: System to surrounding Surroundings to system TEMPERATURE a measure of the average kinetic energy of the particles in a sample of matter. heat flows from high temp. to low temp. Thermometer measures temp. matter expands as its temp. incr Celsius scale. 0oC is freezing pt. of water Kelvin scale 0K is absolute zero – lowest temp. theoretically possible oC = K – 273 K = oC + 273 Diff. substs. incr. temp. diff. amt. with same amt of heat added SPECIFIC HEAT CAPACITY (cp) – The amt. of heat energy required to raise the temp. of 1 gram of a subst. by 1K (or 1 Co) expressed in J / g . K (or J / g . Co) Joule (J) – SI unit of energy Heat energy (q) = m c t Matter and energy are closely related Einstien – E = mc2 implies matter and energy are equivalent can be changed into ea. other