Thermochemistry 1of3
1/14/2013
Principles of General Chemistry, 2nd ed. By M. Silberberg
Chemistry, 8th ed. by W. Whitten, R. Davis, R., M. L. Peck, and G. Stanley.
Chemical Thermodynamics:
Heat and Thermochemistry
Thermodynamics &
Thermochemistry
Thermodynamics is the study of heat and its transformations to and from other forms of energy
Thermochemistry is a branch of thermodynamics that deals with the heat involved with chemical and physical changes Objectives
1. Define thermodynamics & thermochemistry 2. Define energy, heat and other thermodynamic terms
3. Define enthalpy
4. Discuss thermochemical equations
5. Define spontaneity, entropy and Gibb’s free energy
Why study thermochemistry?
•
•
it allows us to predict whether a certain process would occur spontaneously or not however, its limitations is that, it can not predict how fast a reaction would occur (kinetics)
Energy and heat
Thermodynamic terms
ENERGY – the capacity to do work
UNIVERSE = Systems + Surroundings
KINETIC ENERGY – due to motion
POTENTIAL ENERGY – due to position or composition Units: joule (J) = 1 N∙m = 1 kg∙m2/s2 calorie (cal) = 4.184 joules
HEAT – energy transferred between a system and its surroundings as a result of temperature difference
SYSTEMS = substances involved in the physical or chemical changes under investigation SURROUNDINGS = environment around the system
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1/14/2013
Thermodynamic Systems
– composed of particles with their own internal energies (E or U)
– defined by the set of conditions that specify all of its properties
• number of moles and physical states of each substance,
• temperature and pressure of the system
types:
1. OPEN – energy and matter can move in and out of the system freely
2. CLOSED - matter is confined in the system; only energy can move in and out of the system freely
Thermodynamic Systems
2. Systems tend toward a state of maximum disorder.
Common examples of this are:
–
–
–
A mirror shatters when dropped and does not reform.
It is easy to scramble an
Principles of General Chemistry, 2nd ed. By M. Silberberg
Chemistry, 8th ed. by W. Whitten, R. Davis, R., M. L. Peck, and G. Stanley.
Chemical Thermodynamics:
Heat and Thermochemistry
Thermodynamics &
Thermochemistry
Thermodynamics is the study of heat and its transformations to and from other forms of energy
Thermochemistry is a branch of thermodynamics that deals with the heat involved with chemical and physical changes Objectives
1. Define thermodynamics & thermochemistry 2. Define energy, heat and other thermodynamic terms
3. Define enthalpy
4. Discuss thermochemical equations
5. Define spontaneity, entropy and Gibb’s free energy
Why study thermochemistry?
•
•
it allows us to predict whether a certain process would occur spontaneously or not however, its limitations is that, it can not predict how fast a reaction would occur (kinetics)
Energy and heat
Thermodynamic terms
ENERGY – the capacity to do work
UNIVERSE = Systems + Surroundings
KINETIC ENERGY – due to motion
POTENTIAL ENERGY – due to position or composition Units: joule (J) = 1 N∙m = 1 kg∙m2/s2 calorie (cal) = 4.184 joules
HEAT – energy transferred between a system and its surroundings as a result of temperature difference
SYSTEMS = substances involved in the physical or chemical changes under investigation SURROUNDINGS = environment around the system
1
1/14/2013
Thermodynamic Systems
– composed of particles with their own internal energies (E or U)
– defined by the set of conditions that specify all of its properties
• number of moles and physical states of each substance,
• temperature and pressure of the system
types:
1. OPEN – energy and matter can move in and out of the system freely
2. CLOSED - matter is confined in the system; only energy can move in and out of the system freely
Thermodynamic Systems
2. Systems tend toward a state of maximum disorder.
Common examples of this are:
–
–
–
A mirror shatters when dropped and does not reform.
It is easy to scramble an