Chemistry Thermodynamics Exam #1 ||
Questions & Answers (Graded A+)
total energy - ANSWER - sum of all forms of energy of a system (internal, kinetic, and
potential)
internal energy - ANSWER - molecular energy of a system, may exist in sensible, latent,
chemical, and nuclear forms
mechanical energy - ANSWER - form of energy that can be converted to mechanical
work completely and directly by a mechanical device such as an ideal turbine
ways that energy can cross boundary of a closed system - ANSWER - heat or work
pure substance - ANSWER - substance that has a fixed chemical composition
throughout
exists in different phases depending on energy level
compressed/subcooled liquid - ANSWER - liquid that is not about to vaporize
superheated vapor - ANSWER - gas that is not about to condense; temperature and
pressure are independent of each other
saturation temperature and pressure - ANSWER - temperature/pressure that a
substance changes phase at
saturated liquid and vapor - ANSWER - during boiling process, both liquid and vapor
coexist in equilibrium
pressure and temperature dependent on each other
in absence of compressed liquid data... - ANSWER - treat compressed liquid as a
saturated liquid at the given TEMPERATURE
critical point - ANSWER - state beyond which there is no distinct vaporization process
above this point, vapor and liquid are indistinguishable
triple line - ANSWER - all three phases of a substance coexist in equilibrium (triple line
is temperature and pressure)
latent heat of fusion - ANSWER - amount of energy absorbed during melting. It is the
equivalent to the amount of energy released during freezing.
, Latent heat of vaporization - ANSWER - The amount of energy absorbed during
vaporization (equivalent to the energy released during condensation).
Superheated vapor characteristics - ANSWER - Lower pressures at a given T, higher
temperatures at a given P, higher specific volume.
Compressed liquid characteristics - ANSWER - High pressures at a given T, lower
temperatures at a given P, lower specific volumes.
boundary work - ANSWER - work associated with expansion and compression of
substances
isolated system - ANSWER - when no mass, work or energy cross the boundary
mean free path - ANSWER - average distance travelled between collisions of two
molecules
extensive properties - ANSWER - properties that do depend on the amount of matter
present (varies directly with mass)
ex: mass, weight, volume, length, total internal energy
intensive properties - ANSWER - properties that do NOT depend on the amount of
matter present (independent of mass)
ex: color, odor, density, boiling point, melting/freezing, conductivity, hardness
1st Law of Thermodynamics - ANSWER - conservation of energy
energy is a thermodynamics property
2nd Law of Thermodynamics - ANSWER - energy has quality and quantity
actual processes occur in direction of decreasing quality
closed system - ANSWER - system has a fixed mass, no mass can enter or leave
heat and work can cross boundary of a closed system
open system - ANSWER - mass transfer occurs across boundary
thermodynamic equilibrium - ANSWER - maintains thermal, mechanical, phase, and
chemical equilibrium
quasi-static or quasi-equilibrium process - ANSWER - system is practically in
equilibrium at all times
Questions & Answers (Graded A+)
total energy - ANSWER - sum of all forms of energy of a system (internal, kinetic, and
potential)
internal energy - ANSWER - molecular energy of a system, may exist in sensible, latent,
chemical, and nuclear forms
mechanical energy - ANSWER - form of energy that can be converted to mechanical
work completely and directly by a mechanical device such as an ideal turbine
ways that energy can cross boundary of a closed system - ANSWER - heat or work
pure substance - ANSWER - substance that has a fixed chemical composition
throughout
exists in different phases depending on energy level
compressed/subcooled liquid - ANSWER - liquid that is not about to vaporize
superheated vapor - ANSWER - gas that is not about to condense; temperature and
pressure are independent of each other
saturation temperature and pressure - ANSWER - temperature/pressure that a
substance changes phase at
saturated liquid and vapor - ANSWER - during boiling process, both liquid and vapor
coexist in equilibrium
pressure and temperature dependent on each other
in absence of compressed liquid data... - ANSWER - treat compressed liquid as a
saturated liquid at the given TEMPERATURE
critical point - ANSWER - state beyond which there is no distinct vaporization process
above this point, vapor and liquid are indistinguishable
triple line - ANSWER - all three phases of a substance coexist in equilibrium (triple line
is temperature and pressure)
latent heat of fusion - ANSWER - amount of energy absorbed during melting. It is the
equivalent to the amount of energy released during freezing.
, Latent heat of vaporization - ANSWER - The amount of energy absorbed during
vaporization (equivalent to the energy released during condensation).
Superheated vapor characteristics - ANSWER - Lower pressures at a given T, higher
temperatures at a given P, higher specific volume.
Compressed liquid characteristics - ANSWER - High pressures at a given T, lower
temperatures at a given P, lower specific volumes.
boundary work - ANSWER - work associated with expansion and compression of
substances
isolated system - ANSWER - when no mass, work or energy cross the boundary
mean free path - ANSWER - average distance travelled between collisions of two
molecules
extensive properties - ANSWER - properties that do depend on the amount of matter
present (varies directly with mass)
ex: mass, weight, volume, length, total internal energy
intensive properties - ANSWER - properties that do NOT depend on the amount of
matter present (independent of mass)
ex: color, odor, density, boiling point, melting/freezing, conductivity, hardness
1st Law of Thermodynamics - ANSWER - conservation of energy
energy is a thermodynamics property
2nd Law of Thermodynamics - ANSWER - energy has quality and quantity
actual processes occur in direction of decreasing quality
closed system - ANSWER - system has a fixed mass, no mass can enter or leave
heat and work can cross boundary of a closed system
open system - ANSWER - mass transfer occurs across boundary
thermodynamic equilibrium - ANSWER - maintains thermal, mechanical, phase, and
chemical equilibrium
quasi-static or quasi-equilibrium process - ANSWER - system is practically in
equilibrium at all times
