thermodynamics
the science of heat and work
kinetic energy
energy associated with motion
potential energy
results from an object's position i.e. energy possessed by a ball held above the floor
law of conservation of energy
energy can neither be created nor destroyed - total energy of the universe is constant
system
an object, or collection of objects, being studied
surroundings
include everything outside the system that can exchange energy and/or matter with the system
thermal equilibrium
eventually two objects become the same temperature
exothermic process
energy is transferred as heat from a system to its surroundings. The energy of the system decreases, and the energy of the surroundings increases
endothermic process
the opposite of an exothermic process. Energy is transferred as heat from the surroundings to the system, increasing the energy of the system, decreasing the energy of the surroundings
joule
energy quantities
calorie
old measurement of energy. 1 = 4.184 joules
Specific heat capacity
the energy transferred as heat that is required to raise the temperature 1 gram of a substance by one kelvin
q= c x m x delta T
equation used when energy gained or lost as heat when a given mass of a substance is warmed or cooled
q1 + q2 + q3 = 0
law of conservation of mass: in an isolated system the sum of the energy changes within the system must be zero and transferred only as heat
heat of fusion
energy transferred as heat that is required to convert a substance from a solid at its melting point to a liquid
heat of vaporization
energy transferred as heat to convert liquid at its boiling point to a vapor
sublimation
change directly from a solid to a liquid
first law of thermodynamics
(delta U) is the sum of energy transferred as heath between the system and its surroundings (Q) and the energy transferred as work between the system and its surroundings (w)
internal energy
internal energy in chemical system is the sum of the potential and kinetic energies of the atoms, molecules, or ions in the system
state function
no matter how you go from reactants to products in a reaction, the reaction is always the same
standard enthalpy change
the pure, unmixed reactants in their standard states have formed pure, unmixed products in their standard states
standard state
an element or compound is defined as the most stable form of the substance in the physical state that exists at a pressure of 1 bar and at a specific temperature
calorimetry
measurement for the energy evolved or required as heat in a chemical or physical process
Hess's Law
states that if a reaction is the sum of two or more other reactions then it is also for the sum of those reactions