JEE Chemistry- Chemical Thermodynamics Sample Question Paper With Answer Key
Exam Duration: 60 Mins Total Questions : 30
Which of the following is a path function?
- (a)
Temperature
- (b)
Volume
- (c)
Heat
- (d)
Pressure
During the adiabatic process,
- (a)
pressure is maintained constant
- (b)
gas is isothermally expanded
- (c)
there is a perfect heat insulation
- (d)
the system changes heat with surroundings
In a 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)
\(q=0, \triangle T \neq 0, W = 0\)
- (b)
\(q\neq0, \triangle T= 0, W = 0\)
- (c)
\(q=0, \triangle T = 0, W = 0\)
- (d)
\(q=0, \triangle T < 0, W \neq 0\)
If door of a refrigerator is kept open then we get
- (a)
room cooled
- (b)
room heated
- (c)
more heat is passed out
- (d)
No effect on room
\(\triangle_fU^o\) of formation of \(CH_4(g)\) at certain temperature is \(-393\ kJ\ mol^{-1}.\)
The value of \(\triangle _FH^o\) is
- (a)
zero
- (b)
\(< \triangle _f U^0\)
- (c)
\(> \triangle _f U^0\)
- (d)
equal to \( \triangle _f U^-\)
When 401 J of heat is supplied to system and work done by system is 8 J then \(\triangle U\) of system during this process is
- (a)
32 J
- (b)
40 J
- (c)
36 J
- (d)
44 J
On the basis of thermochemical equation (A), (B) and (C), find out which of the algebraic relationships given in option (a) to (d) is correct?
(A) \(C(graphite)+ O_2(g) \longrightarrow CO_2(g);\)
(B) \(C(graphite)+{1\over 2}O_2(g) \longrightarrow CO(g)+1/2\ O_2(g)\longrightarrow CO_2(g)\)
(C) \(CO(g) +1/2O_2(g)\longrightarrow CO_2(g);\)
\(\triangle_cH=z\ kJ\ mol^{-1}\)
- (a)
z = x + y
- (b)
x = y - z
- (c)
x = y + z
- (d)
y = 2z - x
The enthalpy of vaporisation of \(CCl_4\) is \(30.5\ kJ\ mol^{-1}.\) Calculate the heat required for the vaporisation of 284g of \(CCl_4\) at constant pressure. (Molar mass of \(CCl_4\) = 154 g \(mol^{-1}\)).
- (a)
56.2 kJ
- (b)
-56.2 kJ
- (c)
30.5 kJ
- (d)
-30.5 kJ
The heat of atomisation of \(P_4H_4(g)\) and \(PH_3(g)\) is 355 kcal/mol and 228 kcal/mol. The energy of P-P bond is
- (a)
\(102\ kcal\ mol^{-1}\)
- (b)
\(51\ kcal\ mol^{-1}\)
- (c)
\(26\ kcal\ mol^{-1}\)
- (d)
\(204\ kcal\ mol^{-1}\)
\(\triangle G,\) in process of melting of ice at \(-15^oC\), is
- (a)
\(\triangle G=-ve\)
- (b)
\(\triangle G=+ve\)
- (c)
\(\triangle G=0\)
- (d)
All of the above
Using following data \(H_2O(l,373.15K,1atm)\longrightarrow H_2O(g, 373.15K,1atm)\triangle S_1\)
\(H_2O(s, 273.15K,1atm)\longrightarrow H_2O(l, 273.15K,1atm)\triangle S_2\)
Predict which of the following is correct?
- (a)
\(\triangle S_1=\triangle S_2\)
- (b)
\(\triangle S_1>\triangle S_2\)
- (c)
\(\triangle S_1<\triangle S_2\)
- (d)
\(\triangle S_1\) may be greater or smaller than \(\triangle S_2\)
Match of the following and choose the correct option
Reaction | Entropy change |
A. A liquid vaporises | 1. \(\triangle S=0\) |
B. Reaction is non-spontaneous at all temperature and \(\triangle H\) is positive | 2. \(\triangle S\) = positive |
C. Reversible expansion of an ideal gas | 3. \(\triangle S\) = negative |
- (a)
A B C 2 3 1 - (b)
A B C 1 3 2 - (c)
A B C 3 1 2 - (d)
A B C 3 2 1
What is the value of \(\triangle S\) when one mole of ice is converted into water at \(0^oC\)? Given, \(\triangle H_{conversion}=6.0\ kJ\ mol^{-1}\)
- (a)
20.13
- (b)
2.013
- (c)
2.198
- (d)
21.98
Find the entropy change when 2 moles of ideal gas at \(27^o C\) temperature is expanded reversibly from 2 L to 20 L.
- (a)
92.1
- (b)
0
- (c)
4
- (d)
9.2
Temperature and work are
- (a)
extensive properties
- (b)
intensive properties
- (c)
intensive and extensive properties
- (d)
extensive and intensive properties
When a gas expands from 1.5 L to 6.5 L against a constant pressure of 0.50 atm and during this process, the gas also absorbs 100 J of heat. The change in internal energy is
- (a)
153.3 J
- (b)
353.3 J
- (c)
-153.3 J
- (d)
-353.3 J
Consider a gas expands adiabatically from 100 L to 12.0 L against a constant pressure of 0.75 atm. The \(\triangle\ U\) of gas is
- (a)
-853.7 J
- (b)
835.7 J
- (c)
853.7 J
- (d)
-835.7 J
Work done by system is equal to the same extent as the internal energy of an ideal gas decreases, the process is
- (a)
cyclic
- (b)
isothermal
- (c)
adiabatic
- (d)
isolated
The reaction between cyanamide, \(NH_2CN(s)\) and oxygen was allowed to complete and \(\triangle U\) at 300 K was observed to be \(-743\ kJ\ mol^{-1}\)
The value of \(\triangle H\) at 300 K for the following combustion reaction would be=, \(NH_2CN(s)+{3\over 2}O_2(g)\longrightarrow N_2(g)+CO_2(g)+H_2O(l)\)
- (a)
\(-741.75 kJ\ mol^{-1}\)
- (b)
\(-743 kJ\ mol^{-1}\)
- (c)
\(-744.25\ kJ\ mol^{-1}\)
- (d)
\(-740.5 kJ\ mol^{-1}\)
The following data are given as the standard enthalpies of combination of \(C(s), H_2(g)\) and \(CH_4(g)\) are \(-393.5\ kJ\ mol^{-1},-285.8\ kJ\ mol^{-1}\) and \(-890.4\ kJ\ mol^{-1}\) respectively at 298 K. The standard enthalpy of formation of methane \([CH_4(g)] \) is
- (a)
\(+724.42\ kJ\ mol^{-1}\)
- (b)
\(+74.7\ kJ\ mol^{-1}\)
- (c)
\(-114.82\ kJ\ mol^{-1}\)
- (d)
\(-194.62\ kJ\ mol^{-1}\)
The value of \(\triangle -fH^o\) for \(NH_3\) is \(-91.8\ xJ\ mol^{-1}.\) Calculate enthalpy change for the following reaction
\(2NH_3(g)\longrightarrow N_2(g)+3H_2(g)\)
- (a)
\(-91.8\ kJmol^{-1}\)
- (b)
\(91.8\ kJmol^{-1}\)
- (c)
zero
- (d)
\(180.0\ kJmol^{-1}\)
Let any reaction \(A\longrightarrow B\) having \(\triangle _r H=xJ\ mol^{-1}\) completing in 2 sequential steps having enthalpies y and z \(mol^{-1}\) then which of the following is true?
- (a)
X = yy - z
- (b)
x = y + z
- (c)
z = y - x
- (d)
2x = y + z
For the complete combustion of ethanol \(C_2H_5OH(l)+3O_2\rightarrow\ 2CO_2(g)+3H_2O(l)\) the amount of heat produced as measured in bomb calorimeter is 1364.47 \(kJ\ mol^{-1}\) at \(25^oC\). Assuming ideality the enthalpy of combustion, \(\triangle_cH\), for the reaction will be \((R = 8.314\ JK^{-1}mol^{-1})\)
- (a)
\(-1366.95\ kJmol^{-1}\)
- (b)
\(-1361.95\ kJmol^{-1}\)
- (c)
\(-1460.50\ kJmol^{-1}\)
- (d)
\(-1350.50\ kJmol^{-1}\)
The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of \(10\ dm^3\) to volume of \(100 dm^3\) at \(27^oC\) is
- (a)
\(38.3\ J\ mol^{-1}K^{-1}\)
- (b)
\(35.8\ J\ mol^{-1}K^{-1}\)
- (c)
\(32.3\ J\ mol^{-1}K^{-1}\)
- (d)
\(42.3\ J\ mol^{-1}K^{-1}\)
The standard enthalpy of formation of \(NH_3\) is -46.0 \(-46.0\ kJ\ mol^{-1}\) . If the enthalpy of formation of \(H_2\) from its atoms is \(-436\ kJ\ mol^{-1}\) , the average bond enthalpy of N-H bond in \(NH_3\) is
- (a)
\(-964\ kJ\ mol^{-1}\)
- (b)
\(-352\ kJ\ mol^{-1}\)
- (c)
\(+1056\ kJ\ mol^{-1}\)
- (d)
\(-1102\ kJ\ mol^{-1}\)
For a particular reversible reaction at temperature \(T\triangle H\) and \(\triangle S\) were found to be both positive. If \(T_e\) is the temperature at equilibrium, the reaction would be spontaneous when
- (a)
\(T = T_c\)
- (b)
\(T_c>T\)
- (c)
\(T > T_c\)
- (d)
\(T_e\) is 5 times T
In a fuel cell, methanol is used as fuel and oxygen gas is used as an oxidiser. The reaction is \(CH_3OH(l)+{3\over 2}O_2(g)\rightarrow CO_2(g)+2H_2O(l)\)
and \(CO_2(g)\) are \(-166.2,-237.2\) and \(-394.4\ kJ\ mol^{-1}\) respectively.
If the standard enthalpy of combustion of methanol is \(-726\ kJ\ mol^{-1},\) efficiency of the fuel cell will be
- (a)
90%
- (b)
97%
- (c)
80%
- (d)
87%
Standard entropies of \(X_2, X_2\) and \(XY_3\) are 60, 40 and 50 \(J\ K^{-1}mol^{-1}\) respectively. For the reaction \({1\over 2}X_2+{3\over 2}Y_2\rightarrow XY_3, \triangle H=-30\ kJ\ mol^{-1}.\)
This reaction will be at equilibrium at temperature equal to
- (a)
1000 K
- (b)
1250 K
- (c)
500 K
- (d)
750 K
The energies of activation for forward and reverse reaction reactions for \(A_2+B_2 \rightleftharpoons 2AB\) are \(180\ kJ\ mol^{-1}\) and \(200\ kJ\ mol^{-1}\) reactions by \(100\ kJ\ mol^{-1}\). The enthalpy change of the reaction \((A_2+B_2\rightarrow 2\ AB)\) in the presence of catalyst will be
- (a)
\(300\ kJ\ mol^{-1}\)
- (b)
\(120\ kJ\ mol^{-1}\)
- (c)
\(280\ kJ\ mol^{-1}\)
- (d)
\(20\ kJ\ mol^{-1}\)
The enthalpy changes for the following process are listed below
\(Cl_2(g)\longrightarrow 2Cl(g), 243.3\ kJ\ mol^{-1}\)
\(l_2(g)\longrightarrow 2l(g), 151.0\ kJ\ mol^{-1}\)
\(ICl(g)\longrightarrow l(g)+Cl(g), 211.3\ kJ\ mol^{-1}\)
\(l_2(g)\longrightarrow l(g), 62.76\ kJ\ mol^{-1}\)
Standard states for iodine and chlorine are \(I_2(s)\) and \(Cl_2(g)\), standard enthalpy of formation of ICl(g) is
- (a)
\(+244.8\ kJ\ mol^{-1}\)
- (b)
\(-14.6\ kJ\ mol^{-1}\)
- (c)
\(-16.8\ kJ\ mol^{-1}\)
- (d)
\(+16.8\ kJ\ mol^{-1}\)