393157
Description
Mind Map by Rachel Todd, updated more than 1 year ago
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Created by Rachel Todd
over 10 years ago
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Thermodynamics Unit
- Energy
- Can be TRANSFERED
- HEAT
- Change in system's energy
ΔE = q + W
- System
- ex) a solution of HCL
and another of NaOH
were mixed together
in a beaker with a stir
rod
- Solution Chem:
only the HCl and
NaOH
melecules (H+,
OH-)
- Solution Chem:
only the HCl and
NaOH
melecules (H+,
OH-)
- ex) a solution of HCL
and another of NaOH
were mixed together
in a beaker with a stir
rod
- Surrounds
- EVERYTHING ELSE
- EVERYTHING ELSE
- What Causes Chemical Rxns?
- Free Energy ("nature of reactants")
- ΔG = ΔH - TΔS
- ΔG: the max
amount of energy
that can be used to
do work
- ΔH: energy
transferred
as heat
- TΔS: energy
used to create
disorder
- - : thermodynamically favoured (spontaneous)
- + : NOT thermodynamically favoured
- Calculate
- #1: Calculate ΔH from
calorimtry OR Hess's
OR ΔHf; then calculate
ΔS using entropy values;
and then plug in to find
ΔG at a certain temp
- #2: Calculate
ΔG using ΔGfº
values
- (ΔG = ΣnΔGº (products)−ΣnΔGº (reactants))
- (ΔG = ΣnΔGº (products)−ΣnΔGº (reactants))
- #1: Calculate ΔH from
calorimtry OR Hess's
OR ΔHf; then calculate
ΔS using entropy values;
and then plug in to find
ΔG at a certain temp
- ΔG: the max
amount of energy
that can be used to
do work
- ΔG = ΔH - TΔS
- Entropy Δs: measure of disorder
*more random wanted*
- 2nd law: Entropy of
Universe is always
increasing
- ΔS = S(products) - S(reactants)
- ΔSrxn = ΣnSº(products) - ΣnSº(reactants)
- Positive value
is WANTED
- ΔSrxn = ΣnSº(products) - ΣnSº(reactants)
- 2nd law: Entropy of
Universe is always
increasing
- Enthalpy
- 1st Law of
Thermodynamics: cannot
be created or destroyed
- EXO
- ΔH = q = -
- ΔH = q = -
- ENDO
- ΔH = q = +
- ΔH = q = +
- EXO
- can be calculated 4 ways
- #3 Hess's Law
- if a rxn is carried in 1 or several
steps, the overall change in enthalpy
is equal to the sum of the enthalpy
changes for each step
- if a rxn is carried in 1 or several
steps, the overall change in enthalpy
is equal to the sum of the enthalpy
changes for each step
- #2 Calorimeter
- Heat transfer cannot be directly measured
- Heat Capacity
[kJ/K (or Cº)]
- Specific heat
capacity: amount of
heat needed to raise
the temperature of 1
kg of a substance by
1 k [kJ/kg•K (or Cº)]
- ΔH rxn vs Δq rxn
[ΔH = Δq/n]
- total amount of
heat lost or
gained by a rxn
- Using stoichiometry
- total amount of
heat lost or
gained by a rxn
- ΔH rxn vs Δq rxn
[ΔH = Δq/n]
- Specific heat
capacity: amount of
heat needed to raise
the temperature of 1
kg of a substance by
1 k [kJ/kg•K (or Cº)]
- Heat Capacity
[kJ/K (or Cº)]
- Heat transfer cannot be directly measured
- #1 Bond of Enthalpies
- Break bonds NEED energy
- For the image: A
+ B need energy
to break up; C + D
release energy
when formed
- For the image: A
+ B need energy
to break up; C + D
release energy
when formed
- Form bonds REALEASE energy
- ΔH = ΣnBE - ΣnBE
- Σ = sum
- n = # of moles
- BE = bond energy
*from exp't* values
must be given
- Σ = sum
- ΔH = ΣnBE - ΣnBE
- Break bonds NEED energy
- #4 Enthalpy of Formation
- An arbitrary value that indicates how
much heat would be lost/gained from
experimental states
- ΔHº rxn=ΣnΔHºf (products)−ΣnΔHºf (Reactants)
- n: mol
- Most "Hº"'s
will be given
- n: mol
- ΔHº rxn=ΣnΔHºf (products)−ΣnΔHºf (Reactants)
- An arbitrary value that indicates how
much heat would be lost/gained from
experimental states
- #3 Hess's Law
- 1st Law of
Thermodynamics: cannot
be created or destroyed
- Free Energy ("nature of reactants")
- q (+): heat transferred IN
- q (-): heat transferred OUT
- q (-): heat transferred OUT
- w (+): work done ON the system
- w (-): work done BY the system
- w (-): work done BY the system
- ΔE is change in PE
and KE of particles in
a system
- System
- Change in system's energy
ΔE = q + W
- WORK
W = -PΔV
- HEAT
- PE
- KE
- Temperature
- Conversions
- C = K - 273
- C = (5/9)(Fº - 32)
- C = K - 273
- a measure of the
average KE of
particles in a
system
- If KE doubles,
the temp
doubles as well
- If KE doubles,
the temp
doubles as well
- Conversions
- Temperature
- CANNOT BE
CREATED OR
DESTROYED
- Can be TRANSFERED
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