What is Thermochemistry?
Energy: is the capacity to do work (measures in the unit )
• Potential energy is the energy available by virtue of an object’s position.
• Kinectic Energy is the energy of an object due to its motion.
• Thermal Energy is the energy associated with the random motion of atoms and
molecules. (K)
• Chemical energy is the energy stored within the bonds of chemical substances. (P)
• Nuclear energy is the energy stored within the collection of neutrons and protons in the
atom. (P)
Energy Changes in Chemical Reactions
Heat (q) is the transfer of thermal energy between two bodies that are at different
temperatures.
Temperature ( T) is a measure of the average kinetic energy of the particles in a
sample .
Thermal energy: the total quantity of kneitic and poietential energy in a substance.
Temperature ≠ Thermal Energy
, Law of Conservation of Energy: Energy cannot be created or destroyed The system is the
specific part of the universe that is of interest in the study.
System and surroundings:
Energy can not be created or destroyed but can change forms and often it is “ Lost” … as heat
The total energy of a system and its surroundings remains the same— Law of conservation
of energy
Chemical system: the reactants and the products being studied
• Surroundings: all matter not included within the system (reaction). Usually only
consider anything nearby that is capable of exchanging energy or matter.
Types of Systems:
• Open: both energy can be transferred in and out of the system (ex: BBQ )
• Closed: energy can enter and leave the system but matter cannot (ex: glow stick )
• Isolated: neither matter nor energy can move in or out of the system.
Exothermic vs. Endothermic Reactions
Exothermic process is any process that gives off heat – transfers thermal energy from the
system to the surroundings.
(bonds broken < bonds made = takes more energy to make bonds)
Energy: is the capacity to do work (measures in the unit )
• Potential energy is the energy available by virtue of an object’s position.
• Kinectic Energy is the energy of an object due to its motion.
• Thermal Energy is the energy associated with the random motion of atoms and
molecules. (K)
• Chemical energy is the energy stored within the bonds of chemical substances. (P)
• Nuclear energy is the energy stored within the collection of neutrons and protons in the
atom. (P)
Energy Changes in Chemical Reactions
Heat (q) is the transfer of thermal energy between two bodies that are at different
temperatures.
Temperature ( T) is a measure of the average kinetic energy of the particles in a
sample .
Thermal energy: the total quantity of kneitic and poietential energy in a substance.
Temperature ≠ Thermal Energy
, Law of Conservation of Energy: Energy cannot be created or destroyed The system is the
specific part of the universe that is of interest in the study.
System and surroundings:
Energy can not be created or destroyed but can change forms and often it is “ Lost” … as heat
The total energy of a system and its surroundings remains the same— Law of conservation
of energy
Chemical system: the reactants and the products being studied
• Surroundings: all matter not included within the system (reaction). Usually only
consider anything nearby that is capable of exchanging energy or matter.
Types of Systems:
• Open: both energy can be transferred in and out of the system (ex: BBQ )
• Closed: energy can enter and leave the system but matter cannot (ex: glow stick )
• Isolated: neither matter nor energy can move in or out of the system.
Exothermic vs. Endothermic Reactions
Exothermic process is any process that gives off heat – transfers thermal energy from the
system to the surroundings.
(bonds broken < bonds made = takes more energy to make bonds)
