Thermochemistry Flashcards
Work (w)
A force actin through distance
Heat (q)
The flow of energy caused by a temperature difference
Kinetic energy
Energy of motion
Thermal energy
Energy associated with temperature
Potential energy
Energy associated with position or composition
Chemical energy
A form of potential energy associated with positions of electron and nuclei in a system
Law of conservation of energy
Energy cannot be created or destroyed, but it can be transferred from one object or system to another
System
Area of interest –> what you’re studying
Surroundings
Everything else –> ex. The earth is the system and the universe is the surroundings
Thermodynamics
General study of energy and its interconversions
First law of thermodynamics
The total energy of the universe is constant –> law of conservation of energy
Internal energy
U = Ukinetic + Upotential
State function
Function which depends only on the definition of the state, not how it got there –> mountain climbing analogy
Change in internal energy (delta U)
= work + heat
Heat capacity (C)
The quantity of heat required to change a systems temperature by 1 degree Celsius
Enthalpy (H)
The heat evolved in a chemical reaction at a constant pressure
Delta H = qp
Hess’s Law
The change in enthalpy for a stepwise process is the sum of the enthalpy changed of the steps
Standard state - gas
1 atm
Standard state - liquid or solid
1 atm
Standard state - solution
1 mol/L –> 1M
Standard enthalpy
The change in enthalpy when all the reactants and products are in their standard states
Standard formation of enthalpy
The change in enthalpy when 1 mol of compound forms from its constituent elements in their standard states
1 bar.L = x J
X = 100
