Unit 6 Flashcards
Energy
capacity to do work or produce heat
In chemistry we are concerned with,…
heat transfer that occurs during chemical reactions
law of conservation of energy
energy of the universe is constant
Potential energy is due to
position or composition
PE is able to be
converted to work when used
Kinetic energy depends on
mass and velocity of object
energy is able to be converted from ____ to ____
PE to Kinetic energy
Two ways to transfer energy
heat and work
Heat involves the transfer …
energy btwn two objects at different temperatures
heat moves from ….
high to low
work
force acting over a distance
PE is transfered through work ….
from one object to another
States function/state property
energy
Function/properrty depends on…
present state of matter only
non state functions
work and heat
Energy changes are independent of the pathway taken because…
measured value is always the same
Two parts universe is divided into
System & Surroundings
System
part of the universe we wish to focus our attention on
Example of systems
products and reactants
Surroundings
everything else in the universe
Example of surroundings
container the reaction takes place in
In chem, we always take…
systems point of view
exothermic
system to surroundings
endothermic
surroundings to system
first law of thermodynamics
energy of universe is constant
Internal energy of system equals
sum of ke & pe
In delta E= q + w, the sign reflects
systems point of view
system works on surroundings w is ___ because _____
- because work flows out of system
surroundings are working on the system w is ____ because ____
+ because energy will flow into the system
if gas is expanding w is…
negative
if gas is compressing w is…
positive
Is enthalpy a state function or nonstate function?
state function (fixed)
Enthalpy
measurement of the flow of heat in a system
Calorimetry
device used to determine the heat associated w a chemical reaction
calorimetry is based upon…
temperature changes
