Thermochemistry Flashcards
It refers to the average kinetic energy of particles.
Temperature
The part of the universe being studied or to
which attention is focused.
System
A process in which a system absorbs heat
from its surroundings.
Endothermic process
Which is an example of an endothermic process?
Boiling of water
Melting of ice
Melting of ice
It is the capacity to do work or supply heat.
Energy
The rest of the universe
outside the system.
Surroundings
Types of Systems
Allows the exchange of
both energy (heat) and
matter with surroundings.
Open System
Types of Systems
Allows the exchange of
energy (heat) only with
surroundings.
Closed System
Types of Systems
Allows neither energy nor
matter to be exchanged
with surroundings.
Isolated System
Transfers from object with
higher temperature to object
with lower temperature.
HEAT
It is a type of reaction if the system absorbs
heat from its surroundings.
Endothermic Process
It is a type of reaction if the system gives
off heat to the surroundings.
Exothermic Process
Endothermic or Exothermic
Condensation
Exothermic
Endothermic or Exothermic
Evaporation
Endothermic
Endothermic or Exothermic
Burning of coal
Exothermic
Endothermic or Exothermic
Photosynthesis
Endothermic
What Law?
The total energy of a closed system is neither
created nor destroyed; but can be
transformed from one form to another.
First Law of
Thermodynamics
is the capacity to do work.
Energy
In chemical reaction, __________ energy may be released and converted to heat.
Potential
What Law?
In interactions between system and
surroundings, the total energy remains
constant or energy is not created nor
destroyed.
the heat lost by the
surroundings is gained by the
system, and vice-versa.
Law of Conservation of Energy
What Law?
deals with the interconversion of energy into two forms, work, and heat.
First Law of Thermodynamics
First Law of Thermodynamics=
In any process, the change in energy of a
system is ______ to the heat absorbed by the system and the work done on it
equal
Positive (+) Δesys = _____________ process.
Endothermic
Negative (-) Δesys = _____________ process.
Exothermic
amount of energy required
to raise the temperature of a sample by 1oC.
Heat capacity (C)
amount of energy
required to raise one gram of a
substance by 1oC.
Specific Heat (c)
The amount of heat absorbed or released by a chemical
reaction at a constant atmospheric pressure.
Enthalpy (H)
Enthalpy is an ____________ property.
extensive
The “sea level” reference point for all enthalpy expressions is called the _________________
standard enthalpy of formation (ΔHof)
Substances are said to be in the standard state at __ atm, hence the term “standard enthalpy.”
1
The standard enthalpy of formation of any element in its most stable form is ______.
zero
Is the heat change that
results when 1 mole of
the compound is formed
from its elements at a
pressure of 1 atm.
standard enthalpy of formation (ΔHof)
ΔH is positive = _____________ process.
endothermic
ΔH is negative = _____________ process
exothermic
is the enthalpy of a rxn
carried out at 1 atm
ΔH rxn
stoichiometric coefficient for reactants
m
stoichiometric coefficient for products
n
What Law?
The value of enthalpy (ΔH) for a reaction is the same
whether it occurs in one step or in series of steps.
Hess’s Law
What rule of Hess’ Law
Rule 1
Rule 2
Rule 3
Enthalpy is an extensive property; it depends on the amount of reactants and products
Rule 1
What rule of Hess’ Law
Rule 1
Rule 2
Rule 3
ΔH for a forward rxn is equal in magnitude but opposite in sign to its reverse rxn
Rule 2
What rule of Hess’ Law
Rule 1
Rule 2
Rule 3
ΔH for reaction is the same whether it occurs in one step or in a series of steps
Rule 3
