Chapter 2 Flashcards
Kinetic energy:
the energy associated with the motion of an obkect
Thermal energy:
the energy associate with the temperature of an object
Potential enrgy:
the energy associated with the position or composition of an object
examples of kinetic energy:
electrical, heat/thermal, light/radiant
examples of potential energy:
Nuclear, chemical
The law of conservation of energy states what?
that energy can be neither created nor destroyed. Energy can however, be transffered from one object to another and it can assume different forms.
The first lawof thermodynamics is what?
is the law of energy conservation, the total energy of the universe is constant
what is the Internal Energy (E) of a system?
is the sume of the kinetic and potential energies of all of the particles that compose the system.
is internal energy a state function? why or why not?
Yes, which means that its value depends only on the stae of the system, not on how the system arrived at that state.
if triangle E is positive what direction is energy flow?
If triangle E is negative what direction is energy flow?
\+= energy flows into the system and out of the surroundings -= energy flows into the surroundings anf out of the system
a system can exchange energy with its surroundings through —— and —–
heat and work
are heat and work state functions?
NO! Their values depends on the process
thermal equilibrium:
heat flows from matter with high temp to matter with low temp until both reach the same temp
whats the difference between temperature and heat?
temperature is a measure of thermal energy and heat is the transfer of thermal energy
the constant of proportionality between 1 and triangle T is what?
heat capacity (C) the quantity of heat required to change the temperature of the system by 1 degreed C
the higher the heat capacity of a system the ——- the change in temperature for a given amount of absorbed heat
smaller
heat capacity of an object depends on what?
- the amount of matter being heated- extensive property
2. the type of material
specific heat capacity (Cs):
the amount of heat required to raise the temperature of 1 gram of the substance by 1 degree C. Units are J/gXC
molar heat capacity:
the amount of heat required to raise the temperature of 1 mole of a substance by 1 degrees C. Units J/molXC
are specific and molar heat capacity intensive or extensive properties?
Intensive properties- they depends on the kind of substance being heated not on the amount.
Pressure volume work:
occurs when the force is the result of a volume change against
if w is positive:
if w is negative:
positive: work is done on the system by the surroundings
Negative: Work is done on the surroundings by the system.
If a bomb calorimeter is used what does this tell us about the volume?
constant
If no heat escapes from the calorimeter than what?
the amount of heat gained by the calorimeter must exactly equal that released by the reaction
enthalpy (H):
is the sum of the systems internal energy and the product of its pressure and volume.
which of the following are state functions?
energy, pressure or volume?
all of them!
is enthalpy a state function?
yes
what is the difference between triangle E and triagle H?
triangle E is a measure of all of the energy (heat and work) exchanged with the surroundings, while triangle H is a measure of only the heat exchanged under conditions of constant pressure
endothermic:
absorbs heat from its surroundings
exothermic:
gives off heat to its surroundings
label the following as either endothermic or exothermic?
evaporation, feeezing, deposition, sublimation, metling/fusion, condensation
endothermic: evaporation, metling/fusion, sublimation
exothermic: condensation, freezing, deposition
what is the source of an exothermic chemical reaction?
potential energy
chemical potnetial energy arises from what?
arises primarily from the electrostatic forces between the protons and electrongs that compose the atoms and molecules within the system.
enthalpy of reation or heat of reaction (triangle Hrxn) depends on what?
the amount of material.
Triangle H rxn is an extensive property and therefore depends on what?
the quantity of reactant undergoing reaction.
Hess’s Law:
The change in enthalpy for a stepwise process is the sum of the enthalpy changes of the steps
is triangle Hrxn a state function?
yes becuase it depends only on the initial and final states and not on the pathway the reaction follows.
standard enthalpy change (triangle H degree)
The standard enthalpy change is the change in enthalpy for a process when all reactants and products are in their standard states.
vaporization:
liquid to gas
condensation:
gas to liquid
what is volatile and nonvolatile?
volatile= vaporizes easily nonvolatile= does not vaporize easily
is vaporization or condensation an endothermic process?
vaporization= endothermic condensation= exothermic
heat of vaporization (triangle H vap)
the amount of heat required to vaporize one mole of a liquid to gas
Boiling Point:
temp at which its vapor pressure equals the external pressure
sublimation:
solid to gas
deposition:
gas to solid
is melting endothermic or exothermic?
endothermic! therefore freezing is exothermic
