Thermochemistry Flashcards
Thermochemistry
The study of energy changes that occur during chemical reactions and changes in state
System
The matter that is being observed.
The total amount of reactants and products in a chemical reaction.
Surroundings or environment
Everything outside of the system
Isolated system
The system cannot exchange energy (heat or work) or matter with the surroundings; for example, and insulated bomb calorimeter.
Open system
The system can exchange energy (heat and work) and matter with the surroundings
Closed system
The system can exchange energy (heat and work) but not matter with the surroundings
Process (system)
A change in one or more of its properties (such as concentrations of reactants or products, temperature, or pressure).
First law of thermodynamics
Energy can be transferred and transformed, but it cannot be created or destroyed.
U-internal energy of the system
Q-heat added to system
W-work done by system
Isothermal process
Constant temp. implies that the total internal energy of the system (U) is constant
no change in temp.; change in ΔU=0; Q=W (heat added to the system equals work done by the system)
Adiabatic process
A process in which no heat is transferred to or from the system by its surroundings
When Q = 0, the first law simplifies to ΔU = -W (the change in internal energy of the system is equal to work done on the system)
Isobaric process
Occur when pressure of the system is constant. Does not alter the first law of thermodynamics.
Isochoric (isovolumetric)
A process in which there is no change in volume.
W=0, ΔU=Q
no work done
Spontaneous process
One that can occur without having to be driven by energy from outside source.
coupling
A common method for supplying energy for nonspontaneous reactions is by ___________ nonspontaneous reactions to spontaneous ones
State functions
Describe the system in an equilibrium state.
Path independent
When I am under Pressure and feeling Dense, all I want to do is watch TV and get HUGS.
Pressure (P), density (p), temperature (T), volume (V), enthalpy (H), internal energy (U), Gibbs free energy (G), and entropy (S).
Entropy Equation
Phase diagrams
Graphs the phase equilibria as a function of temperature and pressure for a system.
Phase changes (types)
Exist as characteristic temperature and pressures (they are reversible):
1) Fusion (melting) and freezing (crystallization and solidification)
2) Vaporization (evaporation or boiling) and condensation
3) Sublimation or deposition occur at the boundary between the solid and gas phase.
