Chem #7 Flashcards
system
the matter that is being observed—the total amount of reactants and products in a chemical reaction.
surroundings
Surroundings (environment): everything outside of the system
isolated system
The system cannot exchange energy (heat and work) or matter with the surroundings; for example, an insulated bomb calorimeter.
closed system
the system can exchange energy (heat and work) but not matter with the surroundings; for example, a steam radiator.
open system
the system can exchange both energy (heat and work) and matter with the surroundings; for example, a pot of boiling water
process
when a system experiences a change in one or more of its properties (such as concentrations of reactants or products, temperature, or pressure)
isothermal process
occur when the system’s temperature is constant
Constant temperature implies that the total energy of the system (U) is constant (delta U = 0).
adiabatic process
occur when no heat is exchanged between the system and the environment.
isobaric process
occur when the pressure of the system is constant.
Does not alter the first law but appears as a straight line on the P-V graph.
isochoric
experience no change in volume
Vertical line on the P-V graph, work = 0.
spontaneous process
one that can occur by itself without having to be driven by energy from an outside source.
Spontaneous processes can sometimes be VERY slow.
coupling
a common method for supplying energy for nonspontaneous reactions.
• Ex: The combustion of glucose is exergonic; the formation of peptide bonds is endergonic. Energy from combustion of glucose can be stored in the bonds in GTP, which are then lysed to provide the energy for forming peptide bonds.
state functions
describe the system in an equilibrium state. They cannot describe the process of the system. Useful for comparing one equilibrium state to another.
o Pressure, density, temperature, volume, enthalpy, internal energy, Gibbs free energy, entropy
o Independent of the path (process) taken, but are not necessarily independent of each other
process functions
the pathway taken from one equilibrium state to another o Work (W) and heat (Q) are the most important ones.
state functions only depend on _____
the differences between the final and initial states, not how you get there.
standard conditions
defined because systems can be in different equilibrium states at different temperatures and pressure (for measuring the enthalpy, entropy, and Gibbs free energy changes in a reaction).
o 298 K, 1 atm pressure, 1 M concentrations.
o Used for kinetics, equilibrium, and thermodynamics.
standard conditions versus standard temperature and pressure (STP)
STP used for ideal gas law and is 273 K, 1 atm
standard conditions is 298 K, 1 atm, 1 M, and is used for kinetics, equilibrium, and thermodynamics.
standard state
the most stable form of a substance.
Standard enthalpy, standard entropy, and standard free energy changes
the changes that occur when a reaction takes place under standard conditions
process going solid to liquid
melting, fusion
process going liquid to gas
evaporation, vaporization
: when some of the liquid molecules near the surface have enough kinetic energy to leave the liquid phase and escape into the gaseous phase.
• Endothermic process for which the heat source is the liquid water.
• Each time the liquid loses a high-energy particle, the temperature of the remaining liquid decreases.
process going gas to liquid
condensation
: gases returning to the liquid phase.
• Facilitated by lower pressure or higher temperature.
• Vapor pressure of the liquid: the pressure that the gas exerts over the liquid at equilibrium.
• Boiling point: the temperature at which the vapor pressure of the liquid equals the ambient (external, applied, or incident) pressure
process going liquid to solid
freezing/solidification/crystallization
process going gas to solid
deposition