Studied by 0 people
Looks like no one added any tags here yet for you.
physical chemistry
systematic application of the methods of physics to study chemical systems
development of principles and theories that explain and interpret the behavior of chemical systems
applications of physical chemistry
chemical systems
microscopic - based on the concept of molecules
macroscopic - large scale properties of matter without use of the molecule concept
divisions of physical chemistry
quantum chemistry - concerned with properties of molecules and their reactions and its applications on molecular bonding, atomic structure, and spectroscopy
statistical mechanics - provides a molecular insight to the laws of thermodynamics and allows the calculation of macroscopic thermodynamic properties from molecular properties
thermodynamics - the science of energy and how energy transforms, it involves heat and work and the changes they produce in the states of the system
kinetics - the study of the rate processes such as chemical reactions, diffusion, and flow of charge in an electrochemical cell
thermodynamics
the study of the interrelation between heat, work, and internal energy of a system and its interactions with its environment.
examples of systems:
gas in a container
charging and discharging a battery
chemical reactions
system and surroundings
system - quantity of matter or region in space chosen for study with constant mass but possible variable volume
surrounding - mass or region outside the system
boundary - surface separating system from surroundings
at a given temperature, a system has the following properties:
kinetic energy (KE) - energy associated with motion
potential energy (PE) - energy associated with its position in a field (involving gravity)
internal energy (U) - energy associated with microscopic kinetic energies and the energy of interactions between microscopic components as the microscopic kinetic energy increases with temperature
the following are distinguished from the system
control volume - fixed volume over which mass can pass in and out of its boundary
control surface - boundary of the control volume
comparison of system and control volume:
system - fixed mass but variable volume and closed
control volume - fixed volume but potentially variable mass and open
thermodynamic boundary
the obvious separation between system and surroundings
types of thermodynamic boundaries:
adiabatic (thermal conducting) or non-adiabatic
rigid or non-rigid (moveable)
permeable (allows matter to pass through) or impermeable
thermodynamic systems
closed system - does not have mass flow across the boundary, only energy flow
open system - has both mass and energy flow across their boundaries
isolated system - no interaction between system and surrounding, therefore neither mass nor energy can be transferred across their boundaries
thermodynamic states
state variable - describes the state of a system at time t, but it does not reveal how the system was put into that state
pressure
temperature
volume
moles
internal energy
thermodynamic equilibrium
no changes within the system as the macroscopic properties remain constant with time
for there to be thermodynamic equilibrium, all types of equilibrium must be present:
thermal equilibrium
mechanical equilibrium
chemical equilibrium
phase equilibrium
thermal equilibrium
a system and its surroundings are in thermal equilibrium if there must be no change in properties of the system or surroundings when they are separated by a thermally conducting wall
temperature
a property that describes the flow of energy
energy will flow between two objects in contact, resulting in change of state of these two objects
the energy flows from the object with a higher temperature until some equilibrium condition is established
separatory boundaries:
diathermic - if a change of state is observed when two bodies are brought into contact with one another
adiabatic - if no energy flow is permitted between the two objects in contact
zeroth law of thermodynamics
if A is in thermal equilibrium with B, and B is in thermal equilibrium with C, then C is also in thermal equilibrium with A
thermodynamic temperature scale is Kelvin
mechanical equilibrium
related to pressure
there is no change in pressure at any point of the system with time
whenever the net force on an object is zero, the object is in mechanical equilibrium
pressure exerted by gases
gases can be stored in two separate containers separated by a movable wall. the higher pressure gas will move the wall and compress the lower pressure gas until an equilibrium is established
pressure of gases may be controlled via gas entry and release valves, that are set or controlled to let gases in and out at certain pressure thresholds
chemical equilibrium
no net chemical reactions occurs in the system
no net transfer of matter from on part of the system to the other
concentration of chemical species in the various parts of the system are constant with time
thermodynamic processes and cycles
systems undergo the following:
change of state - implies one or more properties of the system has changed
process - a succession of changes of state, it is assumed that processes are all sufficiently slow such that each stage of the process is near equilibrium
cycle - series of processes that returns to the original state
isothermal - constant temperature
isobaric - constant pressure
isochoric - constant volume
thermodynamic properties
intensive variable
independent of the amount of mass of the system
pressure, temperature, specific volume, density
extensive variable
dependent on the size of the system
total volume, mass
temperature
a thermodynamic property that determines the direction of heat flow
ice point - temperature equilibrium between pure ice and liquid water with air saturated with vapor (0°C at 1 atm)
steam point - temperature equilibrium between pure liquid water and water vapor (100°C at 1 atm)
celsius scale
temperatures are denoted as theta and expressed in degrees celsius
pressure
the amount of equal force applied to a specific area
barometer
invented by torricelli, it is a device used to measure pressure
when the column of mercury is in equilibrium with the atmosphere, the pressure at the base is equal to that from the atmosphere, so the height of the mercury is a measure of the external pressure
manometer
a simple pressure measuring device in which a non-volatile viscous liquid is contained in a U-tube
the pressure in the apparatus or from the atmosphere is directly proportional to the height difference of the two columns
formula:
gauge pressure - pressure relative to atmospheric pressure
absolute pressure - the sum of the gauge pressure and the atmospheric pressure
formula:
note: on thermodynamics, we are almost always concerned with absolute pressure as opposed to gauge pressure, and absolute pressure is nearly always interpreted as P
volume
the amount of space that matter occupies
molar volume - volume occupied by 1 mole of gas in a given set of conditions
formula:
measurements
quantity - a property that is measured
unit - a standard quantity against which a quantity is measured
base units:
length
mass
time
temperature
amount of substance
electric current
derived units
frequency
energy
force
pressure
power
electric charge
electric potential difference
area
volume
density
absorbance
Note 
Flashcard (41)