Ch 6 - Thermochemistry Flashcards
thermochemistry
the study of the relationships between chemistry and energy
Exothermic Reaction
a reaction that gives off energy to the surrondings
Energy
the capacity to do work
Work
the result of a force acting through a distance
heat
the flow of energy caused by temperature differences
energy VS heat/work
Energy - something an object possesses
Heat/work - ways objects exchange energy
kinetic energy
the energy associated with the motion of an object
thermal energy
the energy associated with the temperature of an object.
A type of kinetic energy based on the motion of atoms or molecules within a substance.
potential energy
the energy associated with the position or composition of an object.
chemical energy
the energy associated with the relative positions of electrons and nuclei in atoms and molecules.
law of conservation of energy
energy can neither be created nor destroyed.
It can be:
- Transferred from one object to another
- assume different forms(potential to kinetic to thermal etc)
System
the specific setup being examined.
Example: reactants in a flask or a hand warmer in winter.
Surroundings
The systems surroundings are everything with which the system can exchange energy.
Example: Chemicals in a beaker can react with the solution, the beaker, air, the table, etc
Kintetic Energy equation
KE = 1/2mv^2
KE = kinetic energy m = mass v = velocity(m/s)
Mass
kg
Velocity
m/s
Joule
Named for James Joule.
SI unit of energy.
1 J = (1kg)(m^2/s^2)
Kilojoule
often used instead of the joule.
1 kJ = 1000J
“c” calorie(cal)
1 cal = 4.184 J(exact)
A larger unit than the Joule.
“C” Calorie(Cal) or kilocalorie
This is a kilocalorie.
1 Cal = 1000 cal
or
1 kcal = 1000 cal
or
1 kcal = 4184 J
kilowatt-hour(kWh)
1kWh = (3.60)*(10^6) J
First law of thermodynamics
the total energy of the universe is constant.
The is no free lunch. Everything costs something.
internal energy(E)
the sum of the kinetic and potential energies of all of the particles that compose a system
State function
the value of internal energy depends only on the state of the system not on how the system arrived at that state.
Flying or climbing to 10,000 feet are different avenues but either way you are at 10,000 feet(the state)
the change in state function only accounts for the initial and final states and does not care how it got there.