vocab ch 6 Flashcards
energy
the capacity to do work or cause heat flow
law of conservation of energy
E can be converted from one form to another but can be neither created nor destroyed
potential energy
E of position
kinetic energy
E of motion of an object, dependent on the mass of the object and the square of its velocity (1/2mv2)
heat
E transferred between 2 objects because of a temperature difference between them
work
force acting over distance
pathway
the “specific conditions” E change is NOT dependent on the pathway, work and heat are dependent on the pathway
state function
a property of the system that depends only on its present state
system
the reactants and products of the reaction
surroundings
anything else that is not the system; the reaction container, the room etc
exothermic
E flows out of the system, rxn results in the evolution of heat
endothermic
rxn absorbs E from the surroundings, heat flow is into the system
thermodynamics
the study of E and its interconversions
internal energy
E of a system is defined as the sum of the KE and PE of all the particles of the system
enthalpy
at constant pressure, the change in enthalpy = the E flow as heat a property of a system equal to E + PV where E = internal E of the system P = pressure of the system V = volume of the system
Hess’s law
enthalpy is a state fn: in going from a particular set of reactants to a particular set of products, the enthalpy change is the same whether the rxn takes place in one step or a series of steps
standard enthalpy of formation
the enthalpy change associated with the formation of one mole of a compound at 25*C from its elements, with all substances at their standard states at that temp
fossil fuels
coal, petroleum or natural gas; consists of C based molecules derived from the decomposition of once-living organisms
petroleum
mostly formed from marine organisms, a thick, dark liquid composed mostly of compounds called hydrocarbons
natural gas
mostly formed from marine orgnanisms, usually associated with petroleum deposits, consists mostly of methane but also contains ethane, propane and butane
coal
formed from the remains of plants
greenhouse effect
a warming effect exerted by the earth’s atmosphere due to thermal E retained by absorption of infrared radiation
syngas
synthetic gas, a mixture of CO and H obtained by coal gasificiation
change in E is equal to
the change in the system’s internal E
q + w
where q = heat
w = work
