L1-L2 Flashcards
A set of characteristically quantitative approaches to the study of chemical problems
physical chemistry
Thermodynamics explains ____ reactions occur (aka the ____ ___ of the reactions) and the ____ a reaction generates or requires
why, driving force, energy
Gases form the ___ ___ of many machines (e.g. heat engines and ____). The gas phase is the ____ state of matter to treat theoretically, and it shows ____ behaviour that is _____.
working substance, refrigerators, simplest, limiting, universal
The ___ of a system is defined by a particular set of properties such as ___, ___, and ___. These properties can be related by an algebraic expression called an equation of state, such as the ___ ___ ____
state, temperature, volume, moles, ideal gas law
Ideal gas assumes that the gas molecules do not occupy any ____, and there are no ____ between the gas molecules
volume, interactions
The ideal gas law can describe many gasses at high _____ and low ____
temperature, pressures
A molecular interpretation of the ideal gas law that leads to a relation between internal energy and temperature
kinetic model of gasses
Assumptions for the kinetic model of gasses are that a gas consists of molecules in _____ motion, gas molecules are _____ ____ points, the molecules move in ____ ____ until they collide, and the molecules do not ____ except during collisions
random, infinitesimally small, straight lines, interact
In the kinetic model of gasses, the pressure arises from the force exerted on the ____ of the container when the impacting molecules are _____. We need to know the ___ of each impact and the number of impacts in a given interval. We find that the average ___ ___ ___ of one mole of an ideal gas, in other words the ___ ___, is only dependent on ____
walls, deflected, force, translational kinetic energy, internal energy, temperature
The equipartition principle states that each translational and ____ degree of freedom contributes _____ to the total energy, and each vibrational degree of freedom contributes ______ to the total internal temperature.
rotational, RT/2, RT
Rigid, diatomic molecules have _______, because there are ___ translational, ___ vibrational, and ___ rotational degrees of freedom. However, at room temperature, the ___ ____ ___ is not reached for ______ energy, thus it is not ____. This makes the internal energy of one mole of diatomic molecule, to be ____ at room temperature
U = 7/2RT, 3, 1, 2, high temperature limit, vibrational, excited, U = 5/RT
A monoatomic molecule only has ___ degrees of ____ freedom
3, translational
In real gasses, the ____ ___ of the molecules and the ____ between them lead to deviations from the ideal gas law. Consequently, the internal energy is no longer a function of ____ alone.
finite size, interactions, temperature
The repulsive interaction between molecules (aka the ___ ___), implies that they cannot come closer than a certain ____. The actual volume in which the molecules can move is thus _____ compared with the volume of the container V. Therefore, replace V in the ideal gas law by _____, where b is the volume / ___ occupied by the gas itself
size effect, distance, reduced, V-nb, mole
The energy of ___ one molecule experiences from the other molecules is proportional to the density, n/V. The total energy of attraction is thus proportional to ____. These forces ___ the pressure that the gas exert, and since pressure is energy per volume, the resulting change in pressure is proportional to _______. Thus, the pressure in the ideal gas law is replaced by ______
attraction, (n n/V), reduce, (n^2/v^2), P + a(n^2/v^2)
The compressibility factor is _______. the value is __ for an ideal gas
z = pV/nRT, 1
The virial equation shows that at ____ pressures, one often observes a ___ ___ of z with pressure. This linear behaviour can be described by the first two terms in the general virial equation: ____
moderate, linear dependence, z = PV/nRT = 1 + B2p (P)
The. virial equation is a series _____ in terms of pressure or an ____ power of molar volume, Vm. The virial equation has the most sound ____ foundation and can achieve desirable accuracy
expansion, inverse, theoretical
The interface between the system and the surroundings
boundary
Can exchange both energy and matter with its surroundings
open system
Can exchange energy but not matter with its surroundings
closed system
can exchanged neither energy nor matter with its surroundings
isolated system
a physical property that depends only on the present state of the system and is independent of how the state was prepared and the past history of the system
state function
some examples of state functions
density, internal energy, pressure, volume, temperature
a constant temperature process. (it may be necessary for the surroundings to act as a heat reservoir or sink in order to keep the system temperature fixed, and that in general, the system boundary must permit heat flow)
isothermal process
(P = Psurr = constant) a constant pressure process
isobaric process
a constant volume process
isochoric process
a process in which no heat enters or leaves the system
adiabatic process
a process that releases heat into the surroundings (system loses energy)
exothermic process
a process that absorbs heat from the surroundings (the system gains energy)
endothermic process
In a reversible process, the system is always in _____. The process can be reversed by an ____ ___ of its properties. At the end of a cycle, both the system and surroundings have been returned to their ___ __ without any ___ change to either. Sometimes, this is referred to as a _____ process. The ____ of the process is not predetermined.
equilibrium, infinitesimal change, initial states, permanent, quasi-static, direction
In an irreversible system, the system is not always in ____. At the end of a cycle, the system has been returned to its initial state, but the ____ have not, and experienced a permanent change.
equilibrium, surroundings
Spontaneous processes have a predetermined ___ and are ____.
direction, irreversible
Defines the temperature 0C as 273.15 K
Zeroth law of thermodynamics
States that for an isolated system, the internal energy is constant, and equal to q + w (energy can neither be created or destroyed)
first law of thermodynamics
q and q are not ___ functions, they are path _____
state, dependent
Energy can be exchanged between a closed system through the transfer of ___ or ____
heat, work
an endothermic reaction has a _____ q, while an exothermic reaction has a ____ q
positive, negative
Heat was first thought to be a fluid called ___, which flows from a hot substance to a cooler one. ____ suggested that is a form of energy. He found that he could raise the temperature of a substance by either ___ it or by ___ ___ it
caloric, joule, heating, vigorously stirring
If the surroundings do work on the system, w is _____, and the system gains energy. If the system does work on the surroundings, w is ____ and the system loses energy
positive, negative
Only under ____ (e.g. equilibrium) conditions, does the external pressure equal the pressure of the ____
reversible, system
When a gas expands reversibly, the ____ pressure is matched to the pressure of the ____ at every stage of the expansion. When the steps corresponding to the increase in volume are ______, maximum ___ is done on the _____, while the ____ amount of work is required from the surroundings.
external, gas, infinitesimal, work, surroundings, minimum
The internal energy of an ideal gas ____ __ ___ in an isothermal process, and thus, ____
does not change, q= -w
the measurement of heat
calorimetry
the heat absorbed by an object dividing by the corresponding temperature change
heat capacity
The heat capacity generally depends on whether the ___ or the ____ is kept constant. In general, the heat capacity is not a ____ function because it is path-dependent.
pressure, volume, state
___, ___ and ____ have low heat capacities, while water, ___ and ____ have high heat capacities
brass, copper, stainless steel, liquid, ethanol
Enthalpy is defined as ____ and helps keep track of heat exchange at constant ____.
H = U + PV, pressure
A chemical reaction almost always involves changes in ____.
Heat
the standard enthalpy for its formation from its element in their standard state at a given temperature and pressure
standard enthalpy of formation
the standard enthalpy of formation of an ____ is equal to ___ by definition
element, 0
the pure form of a substance at 1 atm
standard sate of a substance
For a reversible phase transition at constant T and P, change in gibbs free energy equals ___ and ____
0, H = TS
