IN
:
OH
Thermochemistry:
Zainab Modan
,Zainab Modan
THERMOCHEMISTRY
Heat ( form of )
study of matter
energy
or chemical reactions
“The study of energy changes associated with chemical reactions involving heat”
The nature of energy:
Energy : The ability to do work or transfer heat
-Work: energy used to cause an object that has mass to move
-Heat: energy used to cause the temperature of an object to rise
Work and heat are meals by which ENERGY is transferred
Three ways of transferring heat:
Conduction : Convection: Radiation:
-Transfer of heat from a fluid to solid
surface or within a fluid -Transfer of heat into an empty
-Can occur in solids and fluids -It is a combination of bulk fluid motion space in the form of
-It is the transfer of heat (ADVECTION) and random molecular motion electromagnetic waves
across a medium or object (DIFFUSION) -matter that is at a finite
which are in PHYSICAL -For convection to happen cool air falls while temperature emits energy in space
CONTACT warm air rises —> in a circular motion in form of electromagnetic waves
Units of energy:
kg.ru?s--kilojoule
of CJ ) 1J I
SI unit
energy
→
joule : =
-
→ KJ : I KJ = 1000J
calorie 1cal amount of heat
unit
energy needed raise
SI Ccal ) : G. 184J →
-
→
non - =
to
the temperature of water
1g by 1°C
-
Nutritional / Food calorie ,
Cal :
1cal =
1000cal = 1kcal
Types of energy:
All objects and molecules can have 2 kinds of energy :
1. KINETIC ENERGY ( Ea) :
energy object possesses due to its motion
2. POTENTIAL ENERGY ( Ep) :
energy object possesses based on its position relative to other objects
, Kinetic energy :
Zainab Modan
Energy an object possesses due to its motion
all
objects have of motion Ek=o
energy
-
Ept
speed
1- Ekta
ÉK = z my §
↳ mass
-
KE a m
b v
-
atoms 4 molecules have mass
} in motion i have KE of Ek
Potential energy:
Energy an object possesses based on its position relative to other objects or
chemical composition
-
Seen when a force acts on an
object
-
Force is a push or pull on an
object
Mass
g) height relative to ref point
Lf
.
Ep =
mg
2
gravitational
constant ( 9. 8m54
For 4 molecules force
atoms
gravitational is
negligible it acts macroscopic objects
-
,
as on
3 main types of Potential energy :
1. GRAVITATIONAL POTENTIAL ENERGY
- Energy stored in an object as a result of its vertical position or height
- Most common use if for an object near the surface of the earth where gravitational acceleration can be assumed to be
constant —> 9.8 m/s2
Pegrav =
Mgh
2. ELASTIC POTENTIAL ENERGY
- Potential energy stored as a result of deformation of an elastic object—> stretching a spring
- Equal to work done to stretch sprung, which depends on the SPRING CONSTANT K and the
DISTANCE STRETCHED X
3. CHEMICAL POTENTIAL ENERGY
-Energy stored in chemical bonds between atoms
- It is released when reaction takes place
:
OH
Thermochemistry:
Zainab Modan
,Zainab Modan
THERMOCHEMISTRY
Heat ( form of )
study of matter
energy
or chemical reactions
“The study of energy changes associated with chemical reactions involving heat”
The nature of energy:
Energy : The ability to do work or transfer heat
-Work: energy used to cause an object that has mass to move
-Heat: energy used to cause the temperature of an object to rise
Work and heat are meals by which ENERGY is transferred
Three ways of transferring heat:
Conduction : Convection: Radiation:
-Transfer of heat from a fluid to solid
surface or within a fluid -Transfer of heat into an empty
-Can occur in solids and fluids -It is a combination of bulk fluid motion space in the form of
-It is the transfer of heat (ADVECTION) and random molecular motion electromagnetic waves
across a medium or object (DIFFUSION) -matter that is at a finite
which are in PHYSICAL -For convection to happen cool air falls while temperature emits energy in space
CONTACT warm air rises —> in a circular motion in form of electromagnetic waves
Units of energy:
kg.ru?s--kilojoule
of CJ ) 1J I
SI unit
energy
→
joule : =
-
→ KJ : I KJ = 1000J
calorie 1cal amount of heat
unit
energy needed raise
SI Ccal ) : G. 184J →
-
→
non - =
to
the temperature of water
1g by 1°C
-
Nutritional / Food calorie ,
Cal :
1cal =
1000cal = 1kcal
Types of energy:
All objects and molecules can have 2 kinds of energy :
1. KINETIC ENERGY ( Ea) :
energy object possesses due to its motion
2. POTENTIAL ENERGY ( Ep) :
energy object possesses based on its position relative to other objects
, Kinetic energy :
Zainab Modan
Energy an object possesses due to its motion
all
objects have of motion Ek=o
energy
-
Ept
speed
1- Ekta
ÉK = z my §
↳ mass
-
KE a m
b v
-
atoms 4 molecules have mass
} in motion i have KE of Ek
Potential energy:
Energy an object possesses based on its position relative to other objects or
chemical composition
-
Seen when a force acts on an
object
-
Force is a push or pull on an
object
Mass
g) height relative to ref point
Lf
.
Ep =
mg
2
gravitational
constant ( 9. 8m54
For 4 molecules force
atoms
gravitational is
negligible it acts macroscopic objects
-
,
as on
3 main types of Potential energy :
1. GRAVITATIONAL POTENTIAL ENERGY
- Energy stored in an object as a result of its vertical position or height
- Most common use if for an object near the surface of the earth where gravitational acceleration can be assumed to be
constant —> 9.8 m/s2
Pegrav =
Mgh
2. ELASTIC POTENTIAL ENERGY
- Potential energy stored as a result of deformation of an elastic object—> stretching a spring
- Equal to work done to stretch sprung, which depends on the SPRING CONSTANT K and the
DISTANCE STRETCHED X
3. CHEMICAL POTENTIAL ENERGY
-Energy stored in chemical bonds between atoms
- It is released when reaction takes place
