CHEM 121 Ch.5 Thermochemistry
Studied by 0 people
Call Kai
Learn
Practice Test
Spaced Repetition
Match
Flashcards
Knowt Play1/39
There's no tags or description
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
|---|
No study sessions yet.
40 Terms
thermodynamics
the study of energy and its transformations
thermochemistry
relationships between chemical reactions and energy changes that involve heat
energy
the capacity to do work or transfer heat
potential energy
stored energy within a system due to its position or composition
kinetic energy
the energy of motion. the energy an object possesses due to motion
thermal energy
kinetic energy associated with the random motion of atoms and molecules
_______ is a quantitative measurement of “hot” or “cold”
temperature
heat (q)
transfer of thermal energy between 2 bodies at different temperatures
an object can _____ or _____ heat, it can’t possess or have heat
gain; lose
1 cal = _______
4.184 J
temperature
a measure of the speed at which atoms or molecules are moving
heat is the measure of the ________ energy that is transferred
kinetic
what units measure temperature?
F, C, or K
what is measuring how energy moves or flows?
heat
exothermic
a change that releases heat
endothermic
a change that absorbs heat
heat capacity (C)
the quantity of heat (q) it absorbs or releases when it experiences a temperature of 1C
specific heat capacity (c)
quantity of heat required to raise the temperature of 1g of a substance by 1C
q =
mass * delta temperature
calorimetry
used to measure amounts of heat transferred to or from a substance
delta temperature =
Tfinal - Tinitial
the 1st law of thermodynamics
energy can be converted from one form to another but it is neither created nor destroyed
the system
the portion we single out for study
the surrounding
everything else
the universe
the system + the surroundings
internal energy (E or U)
sum of all kinetic and potential energies of the system
is internal energy a state function?
yes
state functions
change only depends on initial and final conditions
path functions
change depends on “pathway” of the change
delta U =
Ufinal - Uinitial
work done on system
w > 0
work done by system
w < 0
enthalpy (H)
a thermodynamic quantity that equals to heat flow
is enthalpy a state function?
yes
most chemical reactions take place under ______ ________
constant pressure
enthalpy is a ______ property
extensive
enthalpy of a reaction changes signs if the reaction is _______
reversed
enthalpy changes the ______ of reactants and products
states
standard enthalpy of formation
enthalpy change for a reaction in which exactly 1 mole of a substance is formed from free elements in their most stable states under standard state conditions
Hess’s law
if process can be written as the sum of several stepwise processes, the enthalpy of the total process equals the sum of the enthalpy changes of the individual steps