- Energy: measure of a
systems capacity to do work or supply heat
- System: Region of
primary concern from which energy flows out of or into. The system might be
nanoparticles in a container, or consists of the nanoparticles and the container.
- Surroundings: Everything
that can change energy with the system, If the system consists of nanoparticles in a
container, the container could be considered the surroundings, if the container was perfectly
insulated. If the system is the nanoparticles and container, the surroundings consist of
things in contact with the outside of the container.
- Universe: The system plus the
- Work (W): energy expended
during an act of moving an object a distance against an opposing force. W = -Fx
- Heat (q): energy (thermal)
transferred as a result of a temperature difference between a system and the surroundings.
- Working and Heating:
processes by which
energy is transferred
- Law of Conservation of Energy: energy in not created or destroyed in a process, but can be changed in
form. Total energy of the world is constant
- Thermodynamics: study of
energy and its interconversion
- First Law of Thermodynamics:
the energy of the Universe is constant.
- Potential energy: energy
due to position or composition
- gravitational: energy due to relative position of two objects
- electrostatic: energy due to position of charged particles
- chemical potential: energy resulting from attractions among
electrons and nuclei
- Kinetic energy: energy due
to motion. KE = (1/2)mv2.
- mechanical: energy of motion of macroscopic objects
- thermal: energy of motion of nanoscopic objects
- electrical: energy of motion of electron moving in a conductor
- Difference between
- Temperature measure of the average kinetic energy of the
- Heat is energy (thermal) transferred due to temperature
- calorie (cal): the energy
required to raise the temperature of 1.00 g of pure water by 1.00 degree Celsius.
(the dietary cal is actual a Kcal)
- Joule (J): A unit of energy,
which is derived from other units. 1 J = 1.0 kg.m2/s2.
1 cal = 4.184 J.
- heat capacity: quantity of energy
required to increase the temperature of a sample by 1 degree C (unit = cal/oC).
- specific heat capacity: quantity
of energy required to increase the temperature of a 1 gram of sample by 1
degree C (unit = J/g.oC).
- molar heat capacity:
quantity of energy required to increase the temperature of a 1 mol
of sample by 1 degree C (unit = J/mol.oC).
- heat of fusion: quantity of heat
(thermal energy) required to melt 1 g of a solid at its melting point.
- heat of vaporization: quantity of
heat (thermal energy) required to evaporate 1 g of a liquid at its boiling point.
- Endothermic: a process in
which thermal energy must be transferred into a thermodynamic system in order to maintain
- Exothermic: a process in
which thermal energy must be transferred out of a thermodynamic system in order to
maintain constant temperature
- Internal Energy (E): the
total energy of a system; the sum of the individual energies of all substances in the
system; the sum of the kinetic and potential energies of all substances in a
- First Law of Thermodynamics:
Δ E = E2 - E1 = q + W = q - PΔV for PV work of gases. OR Δ
Euniv = Δ Esys
+ Δ Esurr =
- Enthalpy (H): H = E + PV
- Change in Enthalpy:
H2 - H1 = qp, where qp is the heat change at
constant pressure. The quantity of thermal energy into a system
at constant pressure.
- Bond Dissociation Energy (Bond Enthalpy):
The energy required to break a bond between two atoms in a molecule in the
gaseous state to produce atoms in the gaseous state
- Hess's Law
- Standard State: the pure form of a
substance at standard pressure (1 bar), or for a solute at a concentration
of 1 M. (Note:
The standard state of H2O can be pure water at solid, liquid, or
gaseous water - all pure water - at 1 bar).
- Standard reaction enthapy
H0): The reaction enthalpy when
reactants in their standard state change into products in their standard
state (many tables have data fro 250C for convenience only since
the temperature is not defined for the standard state.. Note
differ in combustion reactions, for example, depending on if pure water
in the liquid or gaseous state at 1 bar is produced.
is used for biological reactions in aqueous solutions (at 1 bar),
when all reactants and products are at 1 M concentration except
H+ = 1 x 10-7M, since most biological
reactions occur around pH 7 when H+ = H3O+
= 10-7 M (pH 7.0).
- Standard enthalpy of formation (Δ
Hf0): The standard reaction enthalpy
per mole of substance for the synthesis of a
compound from pure elements in their
most stable state
at 1 bar and at a specified temperature.
- Standard enthalpy of combustion (Δ
Hc0): The standard reaction enthalpy
per mole of substance for the complete
combustion of a compound under standard condition (standard state and 1