-
Express the change in internal
energy of a system when :
(i) No heat is absorbed by the
system from the surroundings, but work (w) is done on the system. What type of
wall does the system have?
(ii) No work is done on the
system, but q amount of heat is taken out from the system and given to the
surroundings. What type of wall does the system have?
(iii) 'w' amount of work is done by the system and q amount of
heat is supplied to the system. What type of system would it be?
View Answer play_arrow
-
Two litres of an ideal gas at a pressure of 10 atm expands
isothermally into a vacuum until its total volume is 10 litres. How much heat
is absorbed and how much work is done in the expansion?
View Answer play_arrow
-
Two litres of an ideal gas at 10 atm expands isothermally
against a constant external pressure of 1 atm to a volume of 10 litres. How
much heat is absorbed and how much work is done by the gas?
View Answer play_arrow
-
Calculate the work done in reversible isothermal expansion
when 2 L of an ideal gas at a pressure of 10atm expands isothermally against 1 atm
pressure to a final volume of 10 L.
View Answer play_arrow
-
If water vapour is assumed to
be a perfect gas, molar enthalpy change for vaporisation of 1 mole of water at
1 bar and\[100{}^\circ C\]is\[41kJ\text{ }mo{{l}^{-1}}\]. Calculate the
internal energy change, when :
(i) 1 mole of water is
vaporised at 1 bar pressure and\[100{}^\circ C\]
(ii) 1 mole of water is converted into ice.
View Answer play_arrow
-
1 g of graphite is burnt in a
bomb calorimeter in excess of oxygen at 298 K and 1 atm pressure according to
the equation.
\[{{C}_{(graphite)}}+{{O}_{2}}(g)\to
C{{O}_{2}}(g)\]
During the reaction, temperature rises from 298 K to 299K.
If the heat capacity of the bomb calorimeter is\[20.7kJ\,{{K}^{-1}}\], what is
the enthalpy change for the above reaction at 298 K and 1 atm?
View Answer play_arrow
-
A swimmer coming out from a
pool is covered with a film of water weighing about 18 g. How much heat must be
supplied to evaporate this water at 298 K? Calculate the internal energy of
vaporisation at\[100{}^\circ C\].
\[{{\Delta }_{vap}}{{H}^{{}^\circ }}\]for water at \[373K=40.66kJ\,mo{{l}^{-1}}\]
View Answer play_arrow
-
The combustion of one mole of benzene takes place at 298 K
and 1 atm. After combustion, \[C{{O}_{2}}\](g) and\[{{H}_{2}}O(l)\] are
produced and 3267.0 kJ of heat is liberated. Calculate the standard enthalpy of
formation,\[{{\Delta }_{f}}{{H}^{{}^\circ }}\]of benzene. Standard enthalpies
of formation of \[C{{O}_{2}}\](g) and \[{{H}_{2}}O(l)\]are \[-393.5kJ\,mo{{l}^{-1}}\] and\[-285.83kJ\,mo{{l}^{-1}}\]
respectively.
View Answer play_arrow
-
Predict in which of
the following, entropy increases/decreases?
(i) A liquid
crystallizes into a solid.
(ii)
Temperature of a crystalline solid is raised from 0 K to\[115K.\]
(iii) \[2NaHC{{O}_{3}}(s)\to
N{{a}_{2}}C{{O}_{3}}(s)+C{{O}_{2}}(g)+{{H}_{2}}O(g)\]
(iv)\[{{H}_{2}}(g)\to
2H(g)\]
View Answer play_arrow
-
For oxidation of iron:
\[4Fe(s)+3{{O}_{2}}(g)\to
2F{{e}_{2}}{{O}_{3}}(s);\] entropy change is\[-549.4J{{K}^{-1}}mo{{l}^{-1}}\]
at 298K. Inspite of negative entropy change of this reaction, why is the
reaction spontaneous?
\[{{\Delta }_{r}}{{H}^{{}^\circ }}\]for this reaction is\[-1648\times
{{10}^{3}}J\,mo{{l}^{-1}}\].
View Answer play_arrow
-
Calculate\[\Delta
{{G}^{{}^\circ }}\]for the conversion of oxygen to ozone, \[(3/2){{O}_{2}}(g)\rightleftharpoons
{{O}_{3}}(g)\]at \[298K\], if\[{{K}_{p}}\]for this conversion is\[2.47\times
{{10}^{-29}}\].
View Answer play_arrow
-
Find out the value of equilibrium
constant for the following reaction at 298 K:
\[2N{{H}_{3}}(g)+C{{O}_{2}}(g)\rightleftharpoons
N{{H}_{2}}CON{{H}_{2}}(aq)+{{H}_{2}}O(l)\]
Standard Gibbs free energy change\[\Delta {{G}^{{}^\circ
}}\]at the given temperature is\[-13.6kJ\,mo{{l}^{-1}}\] .
View Answer play_arrow
-
At 60C, dinitrogen tetroxide is fifty percent dissociated.
Calculate the standard free energy change at this temperature and at one
atmosphere.
View Answer play_arrow
-
Choose the correct
answer. A thermodynamic state function is a quantity:
(i) used to
determine heat changes.
(ii)whose
value is independent of path.
(iii) used
to determine pressure-volume work.
(iv) whose value
depends on temperature only.
View Answer play_arrow
-
For the process to
occur under adiabatic conditions, the correct condition is:
(i)\[\Delta
T=0\] (ii)\[\Delta p=0\]
(iii) \[q=0\] (iv)
\[w=0\]
View Answer play_arrow
-
The enthalpies of
formation of all elements in their standard states are:
(i) unity (ii)
zero
(iii) <
0
(iv) different for
each element
View Answer play_arrow
-
\[\Delta
{{U}^{{}^\circ }}\]of combustion of methane is \[-XkJmo{{l}^{-1}}\]. The value of\[\Delta
{{H}^{{}^\circ }}\] is (i)\[=\Delta {{U}^{{}^\circ }}\] (ii) \[>\Delta {{U}^{{}^\circ }}\]
(iii) \[
View Answer play_arrow
-
The enthalpy of
combustion of methane, graphite and dihydrogen at 298 K are \[-890.3kJmo{{l}^{-1}},\]\[-393.5kJmo{{l}^{-1}}\]and\[-285.8kJmo{{l}^{-1}}\]
respectively. Enthalpy of formation of \[C{{H}_{4}}(g)\] will be:
(i) \[-74.8kJmo{{l}^{-1}}\] (ii)\[-52.27kJmo{{l}^{-1}}\]
(iii)\[+\text{
}74.8kJmo{{l}^{-1}}\] (iv)\[+52.26kJ\text{ }mo{{l}^{-1}}\]
View Answer play_arrow
-
A reaction, \[A+B\to
C+D+q\] is found to have a positive entropy change. The reaction will be:
(i) Possible
at high temperature (ii) Possible only at low temperatures (iii) Not possible
at any temperature(iv) Possible at any temperature.
[Ans. (iv)]
View Answer play_arrow
-
In a process, 701 J of heat is absorbed by a system and 394J
of work is done by the system. What is the change in internal energy for the
process?
View Answer play_arrow
-
The reaction of cyanamide, \[N{{H}_{2}}CN(s)\], with the
dioxygen was carried out in a bomb calorimeter and\[\Delta U\] was found to be
-742.7 kJ/mol at 298 K. Calculate the enthalpy change for the reaction at 298 K.
View Answer play_arrow
-
Calculate the number of kJ of heat necessary to raise the temperature
of 60 g of aluminium from\[35{}^\circ C\]to\[55{}^\circ C\]. Molar heat
capacity of Al is\[24Jmo{{l}^{-1}}{{K}^{-1}}\].
View Answer play_arrow
-
Calculate the
enthalpy change on freezing of 1 mole of water at\[10{}^\circ C\]to ice at\[-10{}^\circ
C\].
\[{{\Delta
}_{f}}H=6.03kJ\,mo{{l}^{-1}}at{{0}^{{}^\circ }}C.\]
\[{{C}_{p}}[{{H}_{2}}O(l)]=75.3\,\,J\,mo{{l}^{-1}}{{K}^{-1}}\]
\[{{C}_{p}}[{{H}_{2}}O(s)]=36.8\,\,J\,mo{{l}^{-1}}{{K}^{-1}}\]
View Answer play_arrow
-
The enthalpy of combustion of carbon to \[C{{O}_{2}}\] is\[~-393.5kJ\text{
}mo{{l}^{-1}}\]. Calculate the heat released upon formation of'35.2g of\[C{{O}_{2}}\]
from carbon and dioxygen gas.
View Answer play_arrow
-
Enthalpies of
formation of
\[CO(g),C{{O}_{2}}(g),{{N}_{2}}O(g)\]and\[{{N}_{2}}{{O}_{4}}(g)\]
are\[-110,-393,+81\]and\[+9.7kJ\,mo{{l}^{-1}}\]respectively. Find the value of\[{{\Delta
}_{r}}H\] for the reaction:
View Answer play_arrow
-
Given:
\[{{N}_{2}}(g)+3{{H}_{2}}(g)\to
2N{{H}_{3}}(g);{{\Delta }_{r}}{{H}^{{}^\circ }}=-92.4\,kJmo{{l}^{-1}}\]
What is the standard enthalpy of formation of gas?
View Answer play_arrow
-
Calculate the
standard enthalpy of formation of\[C{{H}_{3}}OH(l)\]from the following data:
\[C{{H}_{3}}OH(l)+\frac{3}{2}{{O}_{2}}(g)\to
C{{O}_{2}}(g)+2{{H}_{2}}O(l);\]
\[{{\Delta
}_{r}}{{H}^{{}^\circ }}=-726kJmo{{l}^{-1}}\]
\[C(s)+{{O}_{2}}(g)\to
C{{O}_{2}}(g);\]
\[{{\Delta
}_{c}}{{H}^{{}^\circ }}=-393kJ\,mo{{l}^{-1}}\]
\[{{H}_{2}}(s)+\frac{1}{2}{{O}_{2}}(g)\to
H{{O}_{2}}(l);\]
\[{{\Delta
}_{f}}{{H}^{{}^\circ }}=-286kJ\,mo{{l}^{-1}}\]
View Answer play_arrow
-
Calculate the
enthalpy change for the process:
\[CC{{l}_{4}}(g)\to C(g)+4Cl(g)\]
Calculate bond
enthalpy by \[C-Cl\]in \[CC{{l}_{4}}(g)\]
Given:\[\Delta
H_{vap}^{{}^\circ }CC{{l}_{4}}=30.5kJ\,mo{{l}^{-1}}\]
\[{{\Delta
}_{a}}{{H}^{{}^\circ }}(C)=715kJ\,mo{{l}^{-1}}\] (Enthalpy of atomisation)
\[{{\Delta
}_{a}}{{H}^{{}^\circ }}({{l}_{2}})=715kJ\,mo{{l}^{-1}}\] (Enthalpy of
atomisation)
View Answer play_arrow
-
For an isolated system,\[\Delta U=0\], what will be \[\Delta
S\]?
View Answer play_arrow
-
For the reaction at
298 K :
\[2A+B\to C\]
\[\Delta
H=400kJ\,mo{{l}^{-1}},\Delta S=2kJ\,\,{{K}^{-1}}mo{{l}^{-1}}\]
At what temperature
will the reaction become spontaneous considering \[\Delta H\] and \[\Delta S\]
to be constant over the temperature range?
View Answer play_arrow
-
For the reaction,
\[2Cl(g)\to
C{{l}_{2}}(g);\]what are the signs of \[\Delta H\] and \[\Delta S\]?
View Answer play_arrow
-
For the reaction;
\[2A(g)+B(g)\to 2D(g)\]
\[\Delta
{{U}^{{}^\circ }}_{298\,K}=-10.5kJ\] and \[\Delta {{S}^{{}^\circ
}}=-44.1J{{K}^{-1}}\]
Calculate \[\Delta
{{G}^{{}^\circ }}_{298K}\] for the reaction and predict whether the reaction is
spontaneous or not.
View Answer play_arrow
-
The equilibrium
constant for a reaction is 10. What will be the value of \[\Delta
{{G}^{{}^\circ }}?R=8.314J{{K}^{-1}}mo{{l}^{-1}},T=300K.\]
View Answer play_arrow
-
Comment on the
thermodynamic stability of NO(g), given
\[\frac{1}{2}N(g)+\frac{1}{2}{{O}_{2}}(g)\to
NO(g)\]
\[{{\Delta
}_{r}}{{H}^{{}^\circ }}=90kJ\,mo{{l}^{-1}}\]
\[NO(g)+\frac{1}{2}{{O}_{2}}(g)\to
N{{O}_{2}}(g)\]
\[{{\Delta
}_{r}}{{H}^{{}^\circ }}=-74kJ\,mo{{l}^{-1}}\]
View Answer play_arrow
-
Calculate the
entropy change in the surroundings when 1 mole of \[{{H}_{2}}O(l)\] is formed
under standard conditions
\[{{\Delta
}_{f}}{{H}^{{}^\circ }}=-286kJ\,mo{{l}^{-1}}\]
View Answer play_arrow
-
question_answer36)
In the following questions only one
option is correct.
Thermodynamics is not concerned
about....
(a) energy changes involved in a
chemical reaction
(b) the extent to which a
chemical reaction proceeds
(c) the rate at which a reaction
proceeds
(d) the feasibility of a
chemical reaction
View Answer play_arrow
-
question_answer37)
Which of the following
statements is correct?
(a) The presence of reacting
species in a covered beaker is an example of open system.
(b) There is an exchange of
energy as well as matter between the system and the surroundings in a closed system.
(c) The presence of reactants in
a closed vessel made up of copper is an example of a closed system.
(d) The presence of reactants in
a thermos flask or any other closed insulated vessel is an example of a closed
system.
View Answer play_arrow
-
question_answer38)
The state of a gas can be
described by quoting the relationship between ...
(a) pressure, volume,
temperature (b) temperature, amount, pressure
(c) amount, volume, temperature (d)
pressure, volume, temperature, amount
View Answer play_arrow
-
question_answer39)
The volume of gas is reduced to
half from its original volume. The specific heat will ...
(a) reduce to half (b)
be double (c) remain constant (d) increase four
times
View Answer play_arrow
-
question_answer40)
During complete combustion of
one mole of butane, 2658 kJ of heat is released. The thermo chemical reaction
for above change is :
(a) \[2{{C}_{4}}{{H}_{10}}(g)+13{{O}_{2}}(g)\to
8C{{O}_{2}}(g)+10{{H}_{2}}O(l)\]\[{{\Delta }_{c}}H=-2658.0kJ\,mo{{l}^{-1}}\]
(b)
\[{{C}_{4}}{{H}_{10}}(g)+\frac{13}{2}{{O}_{2}}(g)\to
4C{{O}_{2}}(g)+5{{H}_{2}}O(g)\] \[{{\Delta
}_{c}}H=-1329.0kJ\,mo{{l}^{-1}}\]
(c)
\[{{C}_{4}}{{H}_{10}}(g)+\frac{13}{2}{{O}_{2}}(g)\to
4C{{O}_{2}}(g)+5{{H}_{2}}O(l)\] \[{{\Delta }_{c}}H=-2658.0kJ\,mo{{l}^{-1}}\]
(d) \[{{C}_{4}}{{H}_{10}}(g)+\frac{13}{2}{{O}_{2}}(g)\to
4C{{O}_{2}}(g)+5{{H}_{2}}O(l)\] \[{{\Delta }_{c}}H=+2658.0\,kJ\,mo{{l}^{-1}}\]
View Answer play_arrow
-
question_answer41)
\[{{\Delta }_{f}}{{U}^{O-}}\]of
formation of \[C{{H}_{4}}\] (g) at certain temperature is\[-393kJ\,mo{{l}^{-1}}\].
The value of \[{{\Delta }_{f}}{{H}^{O-}}\] is:
(a) zero (b)
\[<{{\Delta }_{f}}{{U}^{O-}}\] (c)\[>{{\Delta
}_{f}}{{U}^{O-}}\] (d) equal to \[{{\Delta
}_{f}}{{U}^{O-}}\]
View Answer play_arrow
-
question_answer42)
In an adiabatic process, no
transfer of heat takes place between system and surroundings. Choose the
correct option for free expansion of an ideal gas under adiabatic condition
from the following :
(a) \[q=0,\Delta T\ne 0,w=0\] (b)\[q\ne
0,\Delta T=0,w=0\]
(c) \[q=0,\Delta T=0,w=0\] (d)
\[q=0,\Delta T<0,w\ne 0\]
View Answer play_arrow
-
question_answer43)
The pressure-volume work for an
ideal gas can be calculated by using the expression \[w=-\int\limits_{{{V}_{i}}}^{{{V}_{f}}}{{{p}_{ex}}dV.}\].
The work can also be calculated from the pV-plot by using the area under the
curve within the specified limits. When an ideal gas is compressed (a)
reversibly or (b) irreversibly from volume \[{{V}_{i}}\] to \[{{V}_{f}}\],
choose the correct option:
(a) w (reversible) = w
(irreversible) (b) w (reversible) < w (irreversible)
(c) w (reversible) > w
(irreversible) (d) w (reversible) = w (irreversible) +\[{{p}_{ex}}\cdot
\Delta V\]
View Answer play_arrow
-
question_answer44)
The entropy change can be
calculated by using the expression \[\Delta S=\frac{{{q}_{rev.}}}{T}\]. When
water freezes in a glass beaker, choose the correct statement amongst the following:
(a) \[\Delta S\] (system) decreases but \[\Delta
S\] (surroundings) remains the same
(b)\[\Delta
S\] (system) increases but \[\Delta S\] (surroundings) decreases
(c)\[\Delta S\] (system) decreases but \[\Delta
S\] (surroundings) increases
(d) \[\Delta S\] (system)
decreases but \[\Delta S\] (surroundings) also decreases
View Answer play_arrow
-
question_answer45)
On the basis of thermo chemical
equations (i), (ii) and (iii),find out which of the algebraic relationships
given in options (a) to (d) is correct:
(i) \[C(graphite)+{{O}_{2}}(g)\to
C{{O}_{2}}(g);\,\,\,{{\Delta }_{r}}H=x\,kJ\,mo{{l}^{-1}}\]
(ii) \[C(graphite)+\frac{1}{2}{{O}_{2}}(g)\to
CO(g);\,\,{{\Delta }_{r}}H=y\,kJ\,mo{{l}^{-1}}\]
(iii) \[CO(g)+\frac{1}{2}{{O}_{2}}(g)\to
C{{O}_{2}}(g);\]\[{{\Delta }_{r}}H=z\,\,kJ\,mo{{l}^{-1}}\]
(a) \[z=x+y\] (b)
\[x=y-z\] (c) \[x=y+z\] (c)\[y=2z-x\]
View Answer play_arrow
-
question_answer46)
Consider the reactions given
below. On the basis of these reactions find out which of the algebraic
relations given in options (a) to (d) is correct?
(i) \[C(g)+4H(g)\to
C{{H}_{4}}(g);\]\[{{\Delta }_{r}}H=x\,kJ\,mo{{l}^{-1}}\]
(ii) \[C(graphite)+2{{H}_{2}}(g)\to
C{{H}_{4}}(g);\]\[{{\Delta }_{r}}H=y\,kJ\,mo{{l}^{-1}}\]
(a) \[x=y\] (b)
\[x=2y\] (c) \[x>y\] (d) \[x<y\]
View Answer play_arrow
-
question_answer47)
The enthalpies of elements in their
standard states are taken as zero. The enthalpy of formation of a compound:
(a) is always negative (b)
is always positive
(c) may be positive or negative (d)
is never negative
View Answer play_arrow
-
question_answer48)
Enthalpy of sublimation of a
substance is equal to:
(a) enthalpy of fusion +
enthalpy of vaporization
(b) enthalpy of fusion
(c) enthalpy of vaporisation
(d) twice the enthalpy of vaporization
View Answer play_arrow
-
question_answer49)
Which of the following in not
correct?
(a)\[\Delta G\]is zero for a
reversible reaction (b)\[\Delta G\] is positive for a
spontaneous reaction
(c)\[\Delta G\]is negative for a
spontaneous reaction (d)\[\Delta G\]is positive for a non-spontaneous
reaction
View Answer play_arrow
-
question_answer50)
In the following questions two or
more options may be correct.
Thermodynamics mainly deals with:
(a)
interrelation of various forms of energy and their transformation from one form
to another
(b) energy changes in the processes
which depend only on initial and final states of the microscopic systems containing
a few molecules
(c) how and at what rate these
energy transformations are carried out
(d) the system in equilibrium
state or moving from one equilibrium state to another equilibrium state.
View Answer play_arrow
-
question_answer51)
In an exothermic reaction, heat
is evolved and system loses heat to the surroundings. For such system:
(a) \[{{q}_{p}}\]will be
negative (b) \[{{\Delta
}_{r}}H\]will be negative
(c) \[{{q}_{p}}\]will be
positive (d) \[{{\Delta
}_{r}}H\]will be positive
View Answer play_arrow
-
question_answer52)
The spontaneity means, having the
potential to proceed without the assistance of external agency. The processes which
occur spontaneously are:
(a) flow of heat from colder to
warmer body
(b) gas in a container
contracting into one comer
(c) gas expanding to fill the
available volume
(d) burning carbon in oxygen to
give carbon dioxide
View Answer play_arrow
-
question_answer53)
For an ideal gas, the work of
reversible expansion under isothermal condition can be calculated by using the
expression \[w=-nRT\ln
\frac{{{V}_{f}}}{{{V}_{i}}}.\]
A sample containing 1.0 mol of
an ideal gas is expanded isothermally and reversibly to ten times of its
original volume, in two separate experiments. The expansion is carried out at
300 K and at 600 K respectively. Choose the correct option :
(a) Work done at 600 K is 20
times the work done at 300 K
(b) Work done at 300 K is twice
the work done at 600 K
(c) Work done at 600 K is twice the work
done at 300 K
(d) \[\Delta U\] = 0 in both cases
View Answer play_arrow
-
question_answer54)
Consider the following reaction between
zinc and oxygen and choose the correct options out of the options given below:
\[2Zn(s)+{{O}_{2}}(g)\to
2ZnO(s);\,\,\,\Delta H=-693.8kJ\,mo{{l}^{-1}}\](a) The enthalpy of two moles of
\[ZnO\]is less than the total enthalpy of two moles of Zn and one mole of
oxygen by 693.8 kJ
(b) The enthalpy of two moles of
\[ZnO\]is more than the total enthalpy of two moles of Zn and one mole of oxygen
by 693.8 kJ
(c) \[693.8kJ\,mo{{l}^{-1}}\]energy
is evolved in the reaction
(d) \[693.8kJ\,mo{{l}^{-1}}\]energy
is absorbed in the reaction
View Answer play_arrow
-
question_answer55)
18.0 g of water completely
vaporises at \[100{}^\circ C\]and 1 bar pressure and the enthalpy change in the
process is\[40.79\text{ }kJ\text{ }mo{{l}^{-1}}\]. What will be the enthalpy
change for vaporizing two moles of water under the same conditions? What is the
standard enthalpy of vaporisation for water?
View Answer play_arrow
-
question_answer56)
One mole of acetore requires
less heat to vaporise than 1 mole of water. Which of the two liquids has higher
enthalpy of vaporisation?
View Answer play_arrow
-
question_answer57)
Standard molar enthalpy of
formation, \[{{\Delta }_{f}}{{H}^{O-}}\] is just a special case of enthalpy of
reaction\[{{\Delta }_{r}}{{H}^{O-}}\]. Is the\[{{\Delta }_{r}}{{H}^{O-}}\]for
the following reaction same as\[{{\Delta }_{f}}{{H}^{O-}}\]? Give reason for your
answer.
\[CaO(s)+C{{O}_{2}}(g)\to
CaC{{O}_{3}}(s);\] \[{{\Delta }_{f}}{{H}^{O-}}=-178.3\,kJ\,mo{{l}^{-1}}\]
View Answer play_arrow
-
question_answer58)
The value of\[{{\Delta
}_{f}}{{H}^{{}^\circ }}\]for \[N{{H}_{3}}\] is\[-9.18kJmo{{l}^{-1}}\].
Calculate enthalpy change for the following reaction:
\[2N{{H}_{3}}(g)\to {{N}_{2}}(g)+3{{H}_{2}}(g)\]
View Answer play_arrow
-
question_answer59)
Enthalpy is an extensive property. In
general, if enthalpy of an overall reaction \[A\to B\] along one route is \[{{\Delta
}_{r}}H\] and\[{{\Delta }_{r}}{{H}_{1}},{{\Delta }_{r}}{{H}_{2}},{{\Delta
}_{r}}{{H}_{3}}...........\]represent enthalpies of intermediate reactions
leading to product B. What will be the relation between\[{{\Delta }_{r}}H\]for
overall reaction and\[{{\Delta }_{r}}{{H}_{1}},{{\Delta }_{r}}{{H}_{2}}......\]etc.
intermediate reactions?
View Answer play_arrow
-
question_answer60)
The enthalpy of atomisation for
the reaction:
\[C{{H}_{4}}(g)\to C(g)+4H(g)\]is\[1665\text{
}kJ\text{ }mo{{l}^{-1}}\]. What is the bond energy of C-H bond?
View Answer play_arrow
-
question_answer61)
Use the following data to
calculate \[{{\Delta }_{lattice}}{{H}^{O-}}\]for\[NaBr.\]\[{{\Delta
}_{sub}}{{H}^{O-}}\]for sodium metal = \[108.4kJ\,mo{{l}^{-1}}\]
lonization enthalpy of sodium = \[496kJ\,mo{{l}^{-1}}\]Electron
gain enthalpy of bromine = \[-325\,kJ\,mo{{l}^{-1}}\]
Bond dissociation enthalpy of
bromine = \[192kJ\,mo{{l}^{-1}}\]
\[{{\Delta }_{f}}{{H}^{O-}}\]for\[NaBr(s)=-360.1kJ\,mo{{l}^{-1}}\]
View Answer play_arrow
-
question_answer62)
Given that \[\Delta H=0\] for
mixing of two gases. Explain whether the diffusion of these gases into each
other in a closed container is spontaneous or not?
View Answer play_arrow
-
question_answer63)
Heat has randomising influence
on a system and temperature is the measure of average chaotic motion of particles
in the system. Write the mathematical relation which relates these three
parameters.
View Answer play_arrow
-
question_answer64)
Increase in enthalpy of the
surroundings is equal to decrease in enthalpy of the system. Will the temperature
of system and surroundings be the same when they are in thermal equilibrium?
View Answer play_arrow
-
question_answer65)
At 298K, \[{{K}_{p}}\] for the
reaction \[{{N}_{2}}{{O}_{4}}(g)\rightleftharpoons 2N{{O}_{2}}(g)\] is 0.98.
Predict whether the reaction is spontaneous or not.
View Answer play_arrow
-
question_answer66)
A sample of 1.0 mol of a mono atomic
ideal gas is taken through a cyclic process of expansion and compression as shown
in fig. What will be the value of \[\Delta H\] for the cycle as a whole?
View Answer play_arrow
-
question_answer67)
The standard molar entropy of \[{{H}_{2}}O(l)\]is\[70J\,{{K}^{-1}}\,mo{{l}^{-1}}\].
Will the standard molar entropy of \[{{H}_{2}}O(s)\] be more, or less than\[70J\,{{K}^{-1}}mo{{l}^{-1}}\]?
View Answer play_arrow
-
question_answer68)
Identify the state functions and
path dependent functions out of the following:
enthalpy, entropy, heat,
temperature, work, free energy
View Answer play_arrow
-
question_answer69)
The molar enthalpy of
vaporisation of acetone is less than that of water. Why?
View Answer play_arrow
-
question_answer70)
Which quantity out of \[{{\Delta
}_{r}}G\] and \[{{\Delta }_{r}}{{G}^{{}^\circ }}\] will be zero at equilibrium?
View Answer play_arrow
-
question_answer71)
Predict the change in internal
energy for an isolated system at constant volume.
View Answer play_arrow
-
question_answer72)
Although heat is a path function
but heat absorbed by the system under certain specific conditions is
independent of path. What are those conditions? Explain.
View Answer play_arrow
-
question_answer73)
Expansion of a gas in vacuum is
called free expansion. Calculate work done and the change in internal energy when
1 litre of ideal gas expands isothermally into vacuum until its total volume is
5 litre.
View Answer play_arrow
-
question_answer74)
Heat capacity\[~{{C}_{p}}\] is
an extensive property but specific heat(s) is an intensive property. What will
be the relation between \[~{{C}_{p}}\]and s for 1 mol of water?
View Answer play_arrow
-
question_answer75)
The difference between \[~{{C}_{p}}\]
and \[{{C}_{V}}\] can be derived using the empirical relation
\[H=U+PV\]
Calculate the difference between \[~{{C}_{p}}\]and\[{{C}_{V}}\]
for 10 moles of an ideal gas.
View Answer play_arrow
-
question_answer76)
If the combustion of 1 g of graphite
produces 20.7 kJ of heat, what will be the molar enthalpy change? Give the significance
of sign also.
View Answer play_arrow
-
question_answer77)
The net enthalpy change of a
reaction is the amount of energy required to break all the bonds in reactant molecules
minus amount of energy required to form all the bonds in the product molecules.
What will be the enthalpy change for the following reaction.
\[{{H}_{2}}(g)+B{{r}_{2}}(g)\to 2HBr(g)\]
Given that bond energy of \[{{H}_{2}},B{{r}_{2}}\]
and \[HBr\]is \[435\text{ }kJmo{{l}^{-1}},\text{ }192\text{ }kJ\text{
}mo{{l}^{-1}}\text{ }and\text{ }368\text{ }kJ\text{ }mo{{l}^{-1}}\]respectively.
View Answer play_arrow
-
question_answer78)
The enthalpy of vaporisation of \[CC{{l}_{4}}\]
is \[30.5kJ\,mo{{l}^{-1}}\]. Calculate the heat required for the vaporisation
of 284 g of\[CC{{l}_{4}}\] at constant pressure. (Molar mass of\[CC{{l}_{4}}=154\text{
}g\,mo{{l}^{-1}}\])
View Answer play_arrow
-
question_answer79)
The enthalpy of reaction for the
reaction:
\[2{{H}_{2}}(g)+{{O}_{2}}(g)\to
2{{H}_{2}}O(l)\]is\[{{\Delta }_{r}}{{H}^{O-}}=-572kJ\,mo{{l}^{-1}}\]
What will be standard enthalpy
of formation of\[{{H}_{2}}O(l)\]?
View Answer play_arrow
-
question_answer80)
What will be the work done on an
ideal gas enclosed in a cylinder, when it is compressed by a constant external
pressure, \[{{p}_{ext}}\] in a single step as shown in figure? Explain
graphically.
View Answer play_arrow
-
question_answer81)
How will you calculate work done
on an ideal gas in a compression, when change in pressure is carried out in infinite
steps?
View Answer play_arrow
-
question_answer82)
Represent the potential
energy/enthalpy change in the following processes graphically.
(a) Throwing a stone from the
ground to roof.
(b) \[\frac{1}{2}{{H}_{2}}(g)+\frac{1}{2}C{{l}_{2}}(g)\rightleftharpoons
HCl(g);\]\[{{\Delta }_{r}}{{H}^{O-}}=-92.32kJ\,mo{{l}^{-1}}\]
In which of the processes
potential energy/enthalpy change is contributing factor to the spontaneity?
View Answer play_arrow
-
question_answer83)
Enthalpy diagram for a
particular reaction is given in figure. Is it possible to decide spontaneity of
a reaction from given diagram? Explain.
View Answer play_arrow
-
question_answer84)
1 mol of a mono atomic gas is
expanded from state (1) to state (2) as shown in figure. Calculate the work
done for the expansion of gas from state (1) to state (2) at 298 K.
View Answer play_arrow
-
question_answer85)
An ideal gas is allowed to
expand against a constant pressure of 2 bar from 10 L to 50 L in one step.
Calculate the amount of work done by the gas. If the same expansion were carried
out reversibly, will the work done be higher or lower than the earlier case?
(Given : 1 L bar = 100 J)
View Answer play_arrow
-
question_answer86)
In some of the following
questions, one option of left column may be correlated to more than one option
in the right column.
Match the following:
|
|
A
|
|
B
|
|
(i)
|
Adiabatic process
|
(a)
|
Heat
|
|
(ii)
|
Isolated system
|
(b)
|
At constant volume
|
|
(iii)
|
Isothermal change
|
(c)
|
First law of thermodynamics
|
|
(iv)
|
Path function
|
(d)
|
No exchange of energy and matter
|
|
(v)
|
State function
|
(e)
|
No transfer of heat
|
|
(vi)
|
\[\Delta U=q\]
|
(f)
|
Constant temperature
|
|
(vii)
|
Law of conservation of energy
|
(g)
|
Internal energy
|
|
(viii)
|
Reversible process
|
(h)
|
\[{{p}_{ext}}=0\]
|
|
(ix)
|
Free expansion
|
(i)
|
At constant pressure
|
|
(x)
|
\[\Delta H=q\]
|
(j)
|
Infinitely slow process which
proceeds through a series of
equilibrium states
|
|
(xi)
|
Intensive property
|
(k)
|
Entropy
|
|
(xii)
|
Extensive property
|
(I)
|
Pressure
|
|
|
|
(m)
|
Specific heat
|
View Answer play_arrow
-
question_answer87)
Match the following processes
with entropy change:
|
|
Reaction
|
|
Entropy change
|
|
(i)
|
A
liquid vaporises
|
(a)
|
\[\Delta S=0\]
|
|
(ii)
|
Reaction
is non-spontaneous at all temperatures and\[\Delta H\]is positive
|
(b)
|
\[\Delta S\]= positive
|
|
(iii)
|
Reversible
expansion of an ideal gas
|
(c)
|
\[\Delta S\]= negative
|
View Answer play_arrow
-
question_answer88)
Match the following parameters
with description for spontaneity:
|
|
\[\Delta \](Parameters)
\[{{\Delta
}_{\mathbf{r}}}{{\mathbf{H}}^{O-}}\,{{\Delta
}_{\mathbf{r}}}{{\mathbf{S}}^{O-}}\,\,{{\Delta
}_{\mathbf{r}}}{{\mathbf{G}}^{O-}}\]
|
|
Description
|
|
(i)
|
+ - +
|
(a)
|
Non-spontaneous at high
temperature
|
|
(ii)
|
- - + at
highT
|
(b)
|
Spontaneous at all
temperatures
|
|
(iii)
|
- + -
|
(c)
|
Non-spontaneous at all temperatures
|
View Answer play_arrow
-
question_answer89)
Match the following:
|
|
Column I
|
|
Column II
|
|
(i)
|
Entropy of vaporisation
|
(a)
|
decreases
|
|
(ii)
|
K for spontaneous process
|
(b)
|
is always
positive
|
|
(iii)
|
Crystalline solid state
|
(c)
|
lowest entropy
|
|
(iv)
|
\[\Delta U\]in adiabatic
expansion of ideal gas
|
(d)
|
\[\frac{\Delta {{H}_{vap}}}{{{T}_{b}}}\]
|
View Answer play_arrow
-
question_answer90)
In the following questions a
statement of Assertion (A) followed by a statement of Reason (R) is given.
Choose the correct option out of the choices given below:
(a) Both A and R are true and R
is the correct explanation of A.
(b) Both A and R are true but R
is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Assertion (A): Combustion
of all organic compounds is an exothermic reaction.
Reason (R): The
enthalpies of all elements in their standard state are zero.
View Answer play_arrow
-
question_answer91)
Assertion (A):
Spontaneous process is an irreversible process and may be reversed by some
external agency.
Reason (R): Decrease in
enthalpy is a contributory factor for spontaneity.
View Answer play_arrow
-
question_answer92)
Assertion (A): A liquid
crystallises into a solid and is accompanied by decrease in entropy.
Reason (R): In crystals,
molecules organise in an ordered manner.
View Answer play_arrow
-
question_answer93)
Derive the relationship between \[\Delta
H\]and \[\Delta U\]for an ideal gas. Explain each term involved in the
equation.
View Answer play_arrow
-
question_answer94)
Extensive properties depend on
the quantity of matter but intensive properties do not. Explain whether the
following properties are extensive or intensive :
Mass, internal energy, pressure,
heat capacity, density, mole fraction, specific heat, molarity, temperature,
molar heat capacity.
View Answer play_arrow
-
question_answer95)
The lattice enthalpy of an ionic
compound is the enthalpy when one mole of an ionic compound present in its gaseous
state, dissociates into its ions. It is impossible to determine it directly by
experiment. Suggest and explain an indirect method to measure lattice enthalpy
of\[NaCl(s)\].
View Answer play_arrow
-
question_answer96)
\[\Delta G\]is net energy available to
do useful work and is thus a measure of "free energy". Show
mathematically that \[\Delta G\] isa measure of free energy. Find the unit of\[\Delta
G\]. If a reaction has positive enthalpy change and positive entropy change, under
what condition will the reaction be spontaneous?
View Answer play_arrow
