SECTION C Flashcards
What is a state function?
A state function is a function or property of a system whose value depends only on the present state, or condition, of the system, not on the path used to arrive at that state.
What is a spontaneous process?
A spontaneous process is a process that occurs in a system without any input of energy from the surroundings.
It is favoured by a decrease in H and an increase in S
How does a plot of probability vs. energy change with increasing temperature? (Maxwell-Boltzmann distribution)
The curve flattens and moves to the right, given that with increasing temperature the probability of finding particles at higher energy increases.
What is the formula of the Maxwell-Boltzmann distribution?
What is the relationship between Kb (Boltzmann constant) and R (gas constant)?
What are the implications of this relationship?
This means that in the Maxwell-Boltzmann distribution, if we use Kb we get the answer in J/molecule, and if we use R we get the answer in J/mol.
What is an intensive property?
One that doesn’t depend on the amount of material present.
More fancy definition: An intensive property is a physical quantity whose value does not depend on the amount of the substance for which it is measured.
Examples:
chemical potential
concentration
density
melting point and boiling point
molar absorptivity
pressure
specific heat capacity
spectral absorption maxima (in solution)
temperature
What is an extensive (additive) property?
One that depends on the amount of material present.
More fancy definition: The value of an additive property is proportional to the size of the system it describes, or to the quantity of matter in the system.
Examples:
energy
entropy
Gibbs energy
length
mass
particle number
number of moles
volume
weight
What is heat?
Heat is the transfer of energy due to the difference in temperature between the system and surroundings. It results in a change in the random motion at atomic/molecular level in the system and surroundings.
What is work?
Work is a transfer of energy to or from a system that results in a coordinated motion of the molecules of a system.
What is the enthalpy of combustion?
Enthalpy change that takes place when a compound burns in oxygen to produce H2O and CO2 under standard conditions.
What is the enthalpy of formation?
The change of enthalpy from the formation of 1 mole of the compound from its constituent elements, with all substances in their standard states and at standard conditions.
How can the enthalpy of combustion be determined?
Calorimetry
What is the first law of thermodynamics?
Also known as the law of conservation of energy, it states that energy cannot be created or destroyed in a chemical reaction.
When energy passes, as work, as heat, or with matter, into or out from a system, its internal energy changes in accord with the law of conservation of energy.
Thus, the first law can be restated as:
“The total energy of an isolated system is constant”
What is the Zeroth law of thermodynamics?
If two systems are in thermal equilibrium respectively with a third system, they must be in thermal equilibrium with each other. This law helps define the notion of temperature.
What is the second law of thermodynamics?
The entropy of any isolated system not in thermal equilibrium almost always increases.
What is Kirchoff’s law? What is one limitation to this law?
The Kirchhoff Law can only be applied to small temperature changes, (<100 K) because over a larger temperature change, the heat capacityis not constant.
What would a graph showing how enthalpy changes as a function of temperature look like?
