Thermodynamics Flashcards
Statement 1: The laws of thermodynamics deal with energy changes of microscopic systems rather than macroscopic systems containing a large number of molecules.
Statement 2: Laws of thermodynamics apply only when a system is in equilibrium or moves from one equilibrium state to another equilibrium
Statement 1 is incorrect and 2 is correct
The laws of thermodynamics deal with energy changes of macroscopic systems involving a large number of molecules rather than microscopic
systems containing a few molecules.
Statement 1:A system in thermodynamics refers to that
part of universe in which observations are
made and remaining universe constitutes
the surroundings.
Statement 2: system as separated from the
surroundings by some sort of wall which may
be real or imaginary called as boundary
Both statements are correct
Internal energy, U of the system may change, when
3 conditions
• heat passes into or out of the system,
• work is done on or by the system,
• matter enters or leaves the system.
Statement 1: W(adiab) is positive when work is done on the
system and the internal energy of system
increases.
Statement 2: if the work is done by the
system, W(adiabatic)will be negative because internal
energy of the system decreases.
Both statements are correct
Statement 1 q is positive, when heat
is transferred from the surroundings to the
system and the internal energy of the system
increases
Statement 2: q is negative when heat is
transferred from system to the surroundings
resulting in decrease of the internal energy of
the system.
Both statements are correct
∆U = q + w is
mathematical statement of the first law of
thermodynamics, which states that
The energy of an isolated system is……………
.
constant
Process or change is said to be
reversible, if 3 conditions
process could, at any moment,be reversed by an infinitesimal change.
process proceeds infinitely slowly by a series of equilibrium states
system and the surroundings are
always in near equilibrium with each other.
Statement 1:An extensive property is a
property whose value is independent of the quantity
or size of matter present in the system.
Statement 2: Properties which depend
on the quantity or size of matter present
are known as intensive properties.
Both statements are incorrect
Extensive: depend on quantity……..
Intensive: are independent of quantity……..
Assertion: For Water a lot of energy is needed to raise its temperature.
Reason: Water has a large heat capacity, When C is large, a given amount of heat results in only a small temperature rise.
Both assertion and reason are correct and reason correctly explain assertion
We define …………. As heat required to raise the temperature of one unit mass of a substance by one degree celsius (or one kelvin)
Specific heat capacity
We can measure energy changes associated
with chemical or physical processes by an
experimental technique called………..
calorimetry
Heat absorbed at constant………..is measured in a bomb
calorimeter
volume
Since the bomb calorimeter is sealed, its volume does not change so no………. Is done as the reaction is carried out at constant…………
Work
Volume
The standard enthalpy of reaction is the
enthalpy change for a reaction when all
the participating substances are in their………….
standard states.
The standard state of a substance at a
specified temperature is its pure form at pressure………
1 bar
The enthalpy change that accompanies
melting of one mole of a solid substance in
standard state is called…………….
standard enthalpy
of fusion or molar enthalpy of fusion,
∆fusH
Amount of heat required to vaporize one
mole of a liquid at constant temperature
and under standard pressure (1bar) is called
its…………
standard enthalpy of vaporization or
molar enthalpy of vaporization,
.
………………is the change in enthalpy when one mole of a solid substance sublimes at a constant temperature and under standard pressure (1bar).
Standard enthalpy of sublimation, subH
Assertion: Thus, it requires less heat to vaporise 1 mol of acetone than it does to vaporize 1 mol of water.
Reason: The magnitude of the enthalpy change depends on the strength of the intermolecular interactions in the substance undergoing the phase transfomations.
Both are correct and R is correct explanation of A
the strong hydrogen bonds between water molecules hold them tightly in liquid phase.
For an organic liquid, such as acetone, the intermolecular dipole-dipole interactions are significantly weaker.
The standard enthalpy change for the formation of one mole of a compound from its elements in their most stable states of aggregations is called………….
standard molar enthalpy of Formation.
By convention, standard enthalpy for formation, of an element in reference state, i.e., its most stable state of aggregation is taken as.
zero
A balanced chemical equation together with the value of its ∆r H is called a…………
thermochemical equation
If a reaction takes place in several steps then its standard reaction enthalpy is the sum of the standard enthalpies of the intermediate reactions into which the overall reaction may be divided at the same temperature.
True or false
True
………………… is defined as the enthalpy change per mole (or per unit amount) of a substance, when it undergoes combustion and all the reactants and products being in their standard states at the specified temperature.
Standard enthalpy of combustion
