Introduction to Thermodynamics

1.1
core
chemistry Introduction to & electronic structure
:
energy change

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,




Thermodynamics kinetics

happens
•

concerned with involved kinetics is
energy changes in a process concerned with how fast process
'
. a
→ chemical
physical
spontaneity
→

→ electrical


allows us to understand whether will happen spontaneous process occurs without an input of energy
•

a process
•




or not
is not easy
.




.

predicting whether a process is spontaneous
does not tell us how long that process will take
]
•


out heat both processes
examples
:
dissolving NaOH in water
gives
to are spontaneous
◦

occur
]
.




NANO } in water takes in heat
dissolving


key Definitions systems & Surroundings
•
words in thermodynamics are used specifically • The system
→
part of the world we are
studying , e. g. a reaction vessel .




force (F) : units → Newtons IN ) The
surroundings
-




-




A force causes an object to its motion , for example
are made i.
F- ma
→
region outside of the
system where measurements ,
e. , rest of the universe .




to accelerate .




with surroundings
systems classified based on
• what they can exchange

•


Pressure ( P) : units : Pascals ( Pa )
system
ISOLATED : no exchange of energy or mass
pressure is the force per unit area


¥
.




surroundings
P =




It CLOSED :
Exchange of energy ( i. e. , heat or worn ) .




system
Work ( w) units Joules II )
•

: mass
:
surroundings
No
exchange of .




Work is a specific type of energy
distance ✗
W=Fx Defined as energy required to move
It
,




against an opposing force .




system OPEN :
Exchange of energy ( i. e. heat , or work ) & mass .




force required to lift
box -




weight mg
distance __
change in height ( oh)
surroundings
↑
-

- -




µMl MMNMy_~- µMMMMNMy_~- It Isobaric : constant P

-_B0✗ __B0× system

surrounding,
150 thermic :
constant T

v ISO Chori c : constant V

weight = mass ( m) * acceleration due to
gravity 19 ) Adiabatic : no heat flow between systems & surroundings
Power ( P) : units : waits ( w)
Power is the work rate the work done per unit
Internal Energy
¥
-




.


P =
time .




total is called its internal energy
"

energy of a system

change in system energy given by
:
•
is

Heat ( q ) : units : Joules II ) ou =
Urinal -
U initial

Heat is specifically thermal energy . •

interested in energy gained or lost by system
to
Defined as
energy flow from one body
Energy Changes
,




another due to a temperature difference .




Temperature (T)
with respect to the
: units : Kelvin ( k ) -




energy changes
are
always given system .




Temperature related to average then : ☐U > O
◦ K =
-273 "
kinetic energy of the molecules
.
If internal energy of system increases

K -

relative to
substance
that make UP a
.
-




absolute zero
decreases then : ☐U < 0
system If internal energy of system
.


◦
c- relative to
Measured relative to something else u
.




freezing point of
water
surroundings



Heat Capacity (c) ( JK )
"
units : Joules per Kelvin If system gains heat energy 191 from
the surroundings the heat
:
f.
,
neat
.




energy change is positive
.



system
raise temperature
Energy required to
surroindings.ge
( = 9- Of a material by 1 K .
> 0
ᵗ
OF .




If system loses heat
energy (g) from the surroundings , the heat

energy change
is
negative .




surro↑ndin9ˢ
Specific Heat capacity Ukg" K ) q< 0
"

Joules per per Kelvin
.


:
units :
kilogram
↑ will be negative
.


If work is done by the
system ,
then w


Energy required to raise temperature of usum




m%
then w will be positive
done on the system
.




W
If work is ,

surroundings
.




[ 1 kg of material by 1 K
= .




"" " B " " ᵗ " " "" energy expended by the system .
"




W

surroundings
Uma K )
" "


Molar Heat capacity : units : Joules per moi per Kelvin

99 required
"" to raise temperature of , mo, ◦ g


÷ 1ˢᵗ Law of Thermodynamics
( = a material by the '




,



Internal energy of an isolated system is constant
Properties
.
•




Intensive & Extensive • The universe 1
everything ) is an isolated system

Intensive properties of a
•

Energy cannot be created or destroyed .




system do not depend on the amount
'



total of both remain constant
& surroundings but energy
-




energy can be transferred between system .




Examples : temperature & density
.




of materials in the system .

.




→ ✓ total U system + U
Extensive properties of a system do depend on the amount of
=

•

surroundings
system can be due to heat or work or both
system Examples
:
changes in internal energy of a
.




material in the .
mass . volume heat ,
capacity .
• the ,




→ ☐U =
qtw