Chemistry - Energetics
Exam Duration: 45 Mins Total Questions : 30
Carbon and carbon monoxide burn in oxygen to give carbon dioxide according to the equations :
\(C(s)+{ O }_{ 2 }(g)\rightarrow { CO }_{ 2 }(g);\Delta H=-394kJ\quad \quad ...(i)\)
\(2CO(g)+{ O }_{ 2 }(g)\rightarrow { 2CO }_{ 2 }(g);\Delta H=-569kJ\quad \quad ...(ii)\)
The heat of formation of carbon monoxide would be
- (a)
- 109.5 kJ
- (b)
+ 109.5 kJ
- (c)
+ 108.5 kJ
- (d)
- 108.5 kJ
A gas absorbs 100 calories of heat energy and is compressed from 10.0 litres to 5.0 litres by applying an external pressure at 2.0 atm. The change in internal energy for the gas is
- (a)
312 cal
- (b)
342 cal
- (c)
426 cal
- (d)
562 cal
Given the reaction at 975\(?\) and 1 atm \(Ca{ CO }_{ 3 }\rightleftharpoons Cao(s)+{ CO }_{ 2 }(g);\Delta H=176kJ\) then \(\Delta\)E is equal to
- (a)
162 kJ
- (b)
165.6 kJ
- (c)
180 kJ
- (d)
186.4 kJ
Which one of the following statements is true for the spontaneous process?
- (a)
\(\Delta\)G increases
- (b)
\(\Delta\)G decreases
- (c)
S decreases
- (d)
\(\Delta\)S = 0
For the chamical reaciton in forward direction at 25\(?\). A + B \(\rightarrow\) AB
- (a)
\(\Delta\)S is positive
- (b)
\(\Delta\)S is negative
- (c)
\(\Delta\)S is 0
- (d)
\(\Delta\)S cannot be predicted
Given that \(\Delta\)H of the formation of CO2 (g) is - 393.13 kJ mole-1 and \(\Delta\)H of the formation of CO(g) is - 110.39 kJ mole-1. The \(\Delta\)H for the raction : \(CO(g)+1/2{ O }_{ 2 }\rightarrow { CO }_{ 2 }(g)\) would be
- (a)
- 282.74 kJ
- (b)
- 393.13 kJ
- (c)
- 503.63 kJ
- (d)
+ 282.74 kJ
Given the following C(s) \(\rightarrow\) C(g); \(\Delta\)H = 170.9 kcal mol-1
\(\frac { 1 }{ 2 } { H }_{ 2 }(g)\rightarrow H(g)\) , \(\Delta\)H = 170.9 kcal mol-1
\(\Delta\)Hr (CH4) = 170.9 kcal mol-1
The average C - H bond energy in CH4 would be
- (a)
+ 99.2 kcal
- (b)
- 99.2 kcal
- (c)
+ 24.5 kcal
- (d)
- 24.5 kcal
Given \(\Delta H\) = 177.9 kJ and \(\Delta S\) = 160.4 kJ mole-1 for the reaction. \(Ca{ CO }_{ 2 }(s)\rightarrow Cao(s)+{ CO }_{ 2 }(s)\) at 298 K; the free energy change per mole for the above reaction would be
- (a)
- 4.90 kJ
- (b)
+ 4.90 kJ
- (c)
+ 130.1 kJ
- (d)
- 130.1 kJ
A man submits to a diet of 9,500 kJ per day and expends energy in all forms to a toal of 12,000 kJ per day. If the energy lost was stored as sucrose (1632 kJ per 100 g), the number of days the man will take to lose 1 kg of sucrose (ignoring water loss) would be
- (a)
6 days
- (b)
6.53 days
- (c)
5 days
- (d)
4 days
The free energy changes \(\Delta G^o\) for the reaction would be : \({ CH }_{ 3 }COOH(l)+{ C }_{ 2 }{ H }_{ 5 }OH(l)\rightarrow \)\({ CH }_{ 3 }COO{ C }_{ 2 }{ H }_{ 5 }(l)+{ H }_{ 2 }O(l)\)
(Given K for the above reaction = 4)
- (a)
- 3.473 kJ mol-1
- (b)
+ 3.473 kJ mol-1
- (c)
+ 1.473 kJ mol-1
- (d)
- 1.473 kJ mol-1
For the equilibrium \({ PCl }_{ 5 }(g)\rightleftharpoons { PCl }_{ 3 }(g)+{ Cl }_{ 2 }(g)\) at 298 K, Kp = 1.8 \(\times\) 107; the value of \(\Delta G^o\) would be
- (a)
44.80 kJ mol-1
- (b)
45.80 kJ mol-1
- (c)
38.80 kJ mol-1
- (d)
80.80 kJ mol-1
Which one of the following statements is not correct?
- (a)
for isochoric process dE = 0
- (b)
for isothermal process dE = 0
- (c)
for adiabatic process dE = 0
- (d)
for isobaric process dE = 0
For a reaction which one of the following is not a condition for spontaneous change or an equilibrium?
- (a)
\(\Delta\)H = -ve and T\(\Delta\)s = 0
- (b)
T\(\Delta\)s = +ve and \(\Delta\)H = 0
- (c)
\(\Delta\)H = T\(\Delta\)s
- (d)
\(\Delta\)H < T\(\Delta\)s, is -ve and reaction is exothermic
Given the following data : C + O2 \(\rightarrow\) CO, \(\Delta\)H = - 94 kcal CO + 1/2 O2 \(\rightarrow\) CO2; \(\Delta\)H = - 67.7 kcal The heat of formation CO calculated from the data would be
- (a)
+ 40.4 kcal
- (b)
+ 26.3 kcal
- (c)
- 26.3 kcal
- (d)
52.6 kcal
The heat of neutralisation of HCl and NaOH under certain condition is - 55.9 kJ and that of HCN by KOH is - 12.1 kJ. The heat of ionisation of HCN is
- (a)
- 68 kJ mol-1
- (b)
- 43.8 kJ mol-1
- (c)
68.8 kJ mol-1
- (d)
43.8 kJ mol-1
The Hess's law is an application of
- (a)
first law of thermodynamics
- (b)
second law of thermodynamics
- (c)
entropy change
- (d)
free change
Free energy change for a reversible process is
- (a)
more than zero
- (b)
less than zero
- (c)
equal to zero
- (d)
NONE OF THESE
Spontaneity of a chemical reaction is decided by the negative change in
- (a)
internal energy
- (b)
entropy
- (c)
enthalpy
- (d)
free energy
The heat evoved in the combustion of benzene is given by the equation \({ C }_{ 6 }{ H }_{ 6 }(l)+71/2{ O }_{ 2 }(g)\rightarrow { 3H }_{ 2 }O(l)+6{ Co }_{ 2 }(g),\) \(\Delta\)H = 781.0 kcal mol-1 Which of the following quantities of heat energy will be evolved when 39 g of benzene is burnt in an open container?
- (a)
122.25 kcal mol-1
- (b)
390.5 kcal mol-1
- (c)
1562.0 kcal mol-1
- (d)
586.75 kcal mol-1
Who had proposed the following equation: \(\Delta\)G = \(\Delta\)H - T\(\Delta\)S
- (a)
Boltzmann
- (b)
Faraday
- (c)
Gibbs Helmholtz
- (d)
Thomson
Which of the following units represents the largest amount of energy?
- (a)
calorie
- (b)
joule
- (c)
erg
- (d)
electron volt
The enthalpy of vaporisation of water is 186.5 J mol-1; the entropy of its vaporisation would be
- (a)
0.5 J K-1 mol-1
- (b)
1.0 J K-1 mol-1
- (c)
1.5 J K-1 mol-1
- (d)
2.0 J K-1 mol-1
Given : C (diamond) + O2 \(\rightarrow\) CO2 ; \(\Delta\)H = - 395 kJ C (graphic) + O2 \(\rightarrow\) CO2 ; \(\Delta\)H = - 395 kJ The heat of formation of diamond from graphite is
- (a)
+ 2.0 kJ
- (b)
- 1.5 kJ
- (c)
- 7.88 kJ
- (d)
+ 78.8 kJ
In a system, N2, H2 and NH3 are said to be in equilibrium when
- (a)
\(\Delta\)G = 0
- (b)
\(\Delta\)G < 0
- (c)
\(\Delta\)H = 0
- (d)
\(\Delta\)G > 0
Which one of the following is likely to have largest value?
- (a)
heat of dissocioation of a diatomic molecule
- (b)
heat of fusion of the same substance as solid
- (c)
heat of vaporisation of the same substance as a liquid
- (d)
heat of sublimation of the same
A solution of 200 ml of 1 M KOH is added to 200 ml of 1 M HCl and the mixture is well shaken. The rise in temperature T1 is noted. The experiment is repeated by using 50 ml of each solution and increase in temperature T2 is again noted. Which of the following is correct?
- (a)
T1 = T2
- (b)
T2 is twice as large as T1
- (c)
T1 is twice as large as T2
- (d)
T1 is four twice as large as T2
A heat engine absoubs heat Q1 at temperature T1, and heat Q2 at temperature T2. Work done by the enge is (Q1 + Q2) J. This data
- (a)
violates 1st law of the thermodynamics
- (b)
violates 1st law of the thermodynamics if Q1 is -ve
- (c)
violates 1st law of the thermodynamics if Q2 is +ve
- (d)
does not violates 1st law of the thermodynamics.
The heat required to raise the temperature of a body by 1 K is called
- (a)
specific heat
- (b)
thermal capacity
- (c)
water equivalent
- (d)
NONE OF THESE
What is the amount of energy needed to raise the temperature of 10.0 g of iron from 25\(^oC\) to 500\(^oC\), if specific heat capacity of iron is 0.45 J(\(^oC\)-1) g-1?
- (a)
2.1 \(\times\) 102 J
- (b)
2.1 \(\times\) 106 J
- (c)
2.1 \(\times\) 106 J
- (d)
2.1 \(\times\) 103 J
A 1.250 g sample of octane (C8H18) is burnt in excess of oxygen in bomb calorimeter. The temperature of calorimeter rises from 294.05 to 300.78 K. If heat capacity of the calorimeter is 8.93 kJ K-1, the heat transferred to the calorimeter would be
- (a)
0.001 kJ
- (b)
0.025 kJ
- (c)
0.55 kJ
- (d)
0.075 kJ