Thermochemistry Flashcards
define work
energy used to cause an object that has mass to move
Define Energy
the ability to do work or transfer heat
define heat
energy is used to cause the temperature of an object to rise
Define kinetic energy and provide the equation
energy an object possess by virtue of its motion
E - 1/2 mv^2
Define potential energy and provide the equation
energy an object possess by vitue of its position or chemical composition
E = kQ1Q2/d
What’s the standard SI unit of Energy
joule
j=kg m^2 /s^2
Define “System”
The molecules wanted to study
Define “surroundings”
everything that’s not the system
If q is positive, what is the reaction?
Endothermic
If q is negative, what is the reaction conisdered?
Exothermic
First Law of Thermodynamics
Energy is neither created nor destroyed
Define Internal Energy
the sum of all kinetic and potential energies of all components of the system
Define Endergonic
When the change in internal energy is greater than 0 (the system absorbed energy from its surroundings)
Define exergonic
When the change in internal energy is less than 0 *(the system released energy to the surroundings)
What the equation to fine internal energy
E= q + w
Define Enthalpy
The heat of a reaction
H = E + PV
Define calorimetry
The measurement of heat flow
Define heat capacity
The amount of energy required to rais the temperature of a substance by 1K (1C)
C = heat absorbed / increase in temperatrue
Define specific heat capactiy
The amount of energy required to raise the temperatue of 1 g of a substance by 1 K
s = q / m (change in T)
Hess’s law states:
if a reaction is carried out in a series of steps, (delta)H for the overall reaction will equal to the sum of the enthalpy changes for the individual steps
hess’s law is calculated how?
(delta)H = the sum of the enthalpy of the products - the sum of the enthalpy of the reactants
Define a spontaneous processes
those that can proceed without any outside intervention
Processes that are spontaneous in one direction are ________________ in the reverse direction
nonspontaneous
Define Entropy (S)
a thermodynamic function that describes the number of arrangements (positions and/or energy levels) that are available to a system existing in a given state; can be thought of as a measure of the randomness of a system
Second Law of Thermodynamics
The second law of thermodynaics states that the entropy of the universe increases for spontaneous processes and the entropy of the universe does not change for reversible processes
If (delta) S univ is positive
then entropy of the universe increases and the process is spontaneous
if (delta) S univ is 0
the process has no tendency to occur and the system is at equilibrium
Entropy tends to increase with increases in
Tempreature
Volume
The number of independently moving molecules
When a solid is dissolved in a solvent
delta S =
The sum of the entropy of products - the sum of the entropy of reactants
What is Gibbs free energy?
-T(delta)S universe
When delta S is positive Gibbs free energy (delta G)
negative
Gibbs is negative
Reaction is spontaneous
Gibbs at 0
The system is at equilibrium
Gibbs is positive
the reaction is spontaneous in the reverse direction
