OAT prep exam QUESTIONS AND VERRIFIED
ANSWERS
Conduction - ANSWER>>direct transfer of energy from molecule to molecule via
direct molecular collsions
What are the best and worst conductors? - ANSWER>>Worst= gases
Best= metals
Convection - ANSWER>>heat transfer by physical motion; only takes place in
fluids and gases. Heat energy is transferred AWAY from the source.
Radiation - ANSWER>>transfer of energy by electromagnetic waves. Radiation can
travel through a hard vacuum.
Ex: energy from sun
specific heat - ANSWER>>c, amount of heat energy needed to raise the
temperature of 1kg by on degree K.
What is the specific heat of water? - ANSWER>>4186 J/kg*K
Heat transfer formula - ANSWER>>Q=mc(Tf-Ti)
Heat of transformation from solid to liquid - ANSWER>>heat of fusion
Heat of transformation from liquid to gas - ANSWER>>heat of vaporization
Temperature Definition - ANSWER>>average kinetic energy of the system
Pressure definition - ANSWER>>Force per unit surface area (F/A)
STP Conditions - ANSWER>>273 K
,1 atm
1 mole gas --> 22.4 L
Ideal Gas law - ANSWER>>PV=nRT
n= 8.31 J/K*mol
Internal Energy of Monoatomic ideal gas - ANSWER>>U = (3/2)nR(Tf-Ti)
*if temperature stays constant, the internal energy stays constant*
How does Q change when heat is added or removed from a system? -
ANSWER>>Heat added: Q>0
Heat removed: Q<0
When is work positive? - ANSWER>>When work is done by the gas (when the gas
loses energy)
When is work negative? - ANSWER>>When work is done on the gas (when the gas
gains energy)
First law of thermodynamics - ANSWER>>Change in Internal Energy (U) = Q - W
Work in thermodynamic process - ANSWER>>work done by a sample of gas is
equal to the area enclosed by its P-V curve
When the volume of a sample of gas decreases, what is the resulting work? -
ANSWER>>Work is done on the gas, therefore the work will be negative
Cyclic processes (Pressure and Volume) - ANSWER>>total work done by the gas is
area enclosed
Final Internal energy = Initial internal energy
Isothermal process - ANSWER>>temperature remains constant
,As pressure of gas increases, the volume decreases (and vice-versa)
*if ideal gas, then Q = W
Isobaric process - ANSWER>>Pressure remains constant
As volume increases, temperature increases
W=P(Vf-Vi)
Isovolumetric process - ANSWER>>volume stays constant
Work = 0
U=Q
Adiabatic expansion/compression - ANSWER>>No heat transfer into/out of the
system
Q=0
U = -W
irreversible process - ANSWER>>all real processes; proceed in definite time order
Ex: dropping a glass onto the floor and it shatters into many pieces, this can't be
undone
reversible process - ANSWER>>system can run initial to final state or final state to
initial state along the same path
Entropy Definition - ANSWER>>degree of disorder of a system
Second Law of thermodynamics - ANSWER>>any thermodynamic process that
moves from one equilibrium state to another, the entropy of the system and its
surrounding environment together will either increase or remain unchanged.
Reaction Rate - ANSWER>>= change in concentration/time for change to occur
Rate Law - ANSWER>>rate = k[A]^x[B]^y
, overall order = x+y
Temperature & Reaction rates - ANSWER>>rate of reaction will double every +10
degree C
Catalysts - ANSWER>>-are not consumed or altered in reaction process
-lowers activation energy
Homogenous catalyst - ANSWER>>catalyst is in same phase as reactants
Heterogenous Catalyst - ANSWER>>catalyst is in different phase as reactants
Equilibrium Constant Characteristics - ANSWER>>-Pure solids or liquids do not
appear in equilibrium constant expression
-Larger Kc (>1000) --> equilibrium favors products
-Smaller Kc (<-1000) --> equilibrium favors reactants
-Intermediate Kc (-1000 to 1000) --> reactants and products are present in similar
amounts at equilibrium
Le Chatelier's Principle - ANSWER>>when a stress is applied to a system at
equilibrium, the system will adjust to minimize the effect of the stress
When more reactant is added, equilibrium will shift towards the products
When more product is added, equilibrium will shift towards the reactants
increase in pressure --> shift equilibrium to lower number of moles present
increase in volume --> equilibrium shift to higher moles present
principle quantum number - ANSWER>>n
overall energy level and size of electron's path
ANSWERS
Conduction - ANSWER>>direct transfer of energy from molecule to molecule via
direct molecular collsions
What are the best and worst conductors? - ANSWER>>Worst= gases
Best= metals
Convection - ANSWER>>heat transfer by physical motion; only takes place in
fluids and gases. Heat energy is transferred AWAY from the source.
Radiation - ANSWER>>transfer of energy by electromagnetic waves. Radiation can
travel through a hard vacuum.
Ex: energy from sun
specific heat - ANSWER>>c, amount of heat energy needed to raise the
temperature of 1kg by on degree K.
What is the specific heat of water? - ANSWER>>4186 J/kg*K
Heat transfer formula - ANSWER>>Q=mc(Tf-Ti)
Heat of transformation from solid to liquid - ANSWER>>heat of fusion
Heat of transformation from liquid to gas - ANSWER>>heat of vaporization
Temperature Definition - ANSWER>>average kinetic energy of the system
Pressure definition - ANSWER>>Force per unit surface area (F/A)
STP Conditions - ANSWER>>273 K
,1 atm
1 mole gas --> 22.4 L
Ideal Gas law - ANSWER>>PV=nRT
n= 8.31 J/K*mol
Internal Energy of Monoatomic ideal gas - ANSWER>>U = (3/2)nR(Tf-Ti)
*if temperature stays constant, the internal energy stays constant*
How does Q change when heat is added or removed from a system? -
ANSWER>>Heat added: Q>0
Heat removed: Q<0
When is work positive? - ANSWER>>When work is done by the gas (when the gas
loses energy)
When is work negative? - ANSWER>>When work is done on the gas (when the gas
gains energy)
First law of thermodynamics - ANSWER>>Change in Internal Energy (U) = Q - W
Work in thermodynamic process - ANSWER>>work done by a sample of gas is
equal to the area enclosed by its P-V curve
When the volume of a sample of gas decreases, what is the resulting work? -
ANSWER>>Work is done on the gas, therefore the work will be negative
Cyclic processes (Pressure and Volume) - ANSWER>>total work done by the gas is
area enclosed
Final Internal energy = Initial internal energy
Isothermal process - ANSWER>>temperature remains constant
,As pressure of gas increases, the volume decreases (and vice-versa)
*if ideal gas, then Q = W
Isobaric process - ANSWER>>Pressure remains constant
As volume increases, temperature increases
W=P(Vf-Vi)
Isovolumetric process - ANSWER>>volume stays constant
Work = 0
U=Q
Adiabatic expansion/compression - ANSWER>>No heat transfer into/out of the
system
Q=0
U = -W
irreversible process - ANSWER>>all real processes; proceed in definite time order
Ex: dropping a glass onto the floor and it shatters into many pieces, this can't be
undone
reversible process - ANSWER>>system can run initial to final state or final state to
initial state along the same path
Entropy Definition - ANSWER>>degree of disorder of a system
Second Law of thermodynamics - ANSWER>>any thermodynamic process that
moves from one equilibrium state to another, the entropy of the system and its
surrounding environment together will either increase or remain unchanged.
Reaction Rate - ANSWER>>= change in concentration/time for change to occur
Rate Law - ANSWER>>rate = k[A]^x[B]^y
, overall order = x+y
Temperature & Reaction rates - ANSWER>>rate of reaction will double every +10
degree C
Catalysts - ANSWER>>-are not consumed or altered in reaction process
-lowers activation energy
Homogenous catalyst - ANSWER>>catalyst is in same phase as reactants
Heterogenous Catalyst - ANSWER>>catalyst is in different phase as reactants
Equilibrium Constant Characteristics - ANSWER>>-Pure solids or liquids do not
appear in equilibrium constant expression
-Larger Kc (>1000) --> equilibrium favors products
-Smaller Kc (<-1000) --> equilibrium favors reactants
-Intermediate Kc (-1000 to 1000) --> reactants and products are present in similar
amounts at equilibrium
Le Chatelier's Principle - ANSWER>>when a stress is applied to a system at
equilibrium, the system will adjust to minimize the effect of the stress
When more reactant is added, equilibrium will shift towards the products
When more product is added, equilibrium will shift towards the reactants
increase in pressure --> shift equilibrium to lower number of moles present
increase in volume --> equilibrium shift to higher moles present
principle quantum number - ANSWER>>n
overall energy level and size of electron's path
