Unit 7 Flashcards
the capacity to do work or to transfer heat
energy
energy used to cause an object with mass to move
work
energy used to cause the temperature of an object to increase
heat
energy of motion
kinetic energy
work =
force TIMES distance
energy at rest; energy of position
potential energy
energy can neither be created nor destroyed but it can be converted from one form to another
law of conservation of energy
the study of energy and its transformations (especially those involving heat)
thermodynamics
all the energy transferred between a system and its surroundings must be accounted for as either heat or work
first law of thermodynamics
the portion of the universe we single out for study
system
the principle, is the rest of the universe
surroundings
heat flows out of the system into the surroundings
exothermic
system is losing heat (q negative)
exothermic
heat that flows into the system from the surroundings
endothermic
system is gaining heat (q positive)
endothermic
work done by an expanding gas
pressure volume worth
amount of kinetic energy transferred from one object to another object as a result of a temperature difference between the two
heat
amount of heat
q (in joules)
mass
m (grams)
specific heat capacity
c (joules/grams degree C)
change in temp
delta T (degree C)
experiments that measure heat
calorimetry experiment
open to atmosphere
coffee cup calorimeter
heat transferred at constant pressure
enthalpy
change in state of matter
phase change
increase the size of the molecular motions and put energy into the sample to increase the size of the molecular motions
going from a solid to a liquid
AND
going from a liquid to a gas
to reverse the process
decrease the size of molecular motions and take energy out of the sample
all the energy transferred between a system and its surroundings must be accounted for as either heat or work
first law of thermodynamics
indicates that something depends only on the initial state of the system and the final state of the system
state functions
only depends on where we started and where we finished (does NOT depend on the path between where we started and where we finished)
state functions
T or F work is a state function
FALSE; work= forceXdistance
determine the enthalpy change for a reaction when it may be experimentally difficult to do so
hess’s law
