Chapter 17 Outline Chemistry

396 WordsSep 20, 20142 Pages
Chapter 17 Outline April 13th 2014 “Thermochemistry” - concerned with heat changes that occur during chemical reactions o Energy - capacity for doing work or supplying heat weightless, odorless, tasteless if within the chemical substances- called chemical potential energy o In studying heat changes, think of defining these two parts: o the system - the part of the universe on which you focus your attention o the surroundings - includes everything else in the universe o The Law of Conservation of Energy states that in any chemical or physical process, energy is neither created nor destroyed. o All the energy is accounted for as work, stored energy, or heat. o Heat flowing into a system from it’s surroundings: o defined as positive o q has a positive value o called endothermic o system gains heat (gets warmer) as the surroundings cool down o Heat flowing out of a system into it’s surroundings: o defined as negative o q has a negative value o called exothermic o system loses heat (gets cooler) as the surroundings heat up o Heat Capacity - the amount of heat needed to increase the temperature of an object exactly 1 degrees Celcius o Depends on both the object’s mass and its chemical composition o To calculate, use the formula: o q = mass (in grams) x T x C o heat is abbreviated as “q” o T = change in temperature o C = Specific Heat o Units are either: J/(g degrees C) or cal/(g degrees C) o Calorimetry - the measurement of the heat into or out of a system for chemical and physical processes. o Based on the fact that the heat released = the heat absorbed o The device used to measure the absorption or release of

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