IISER Chemistry - Energetics
Exam Duration: 45 Mins Total Questions : 30
Which one of the following statements is wrong?
- (a)
The brach of chemistry which deals with energy changes involved in chemical reactions, is called chemical energetics.
- (b)
Renewable source of energy is also called non-convetional source of energy.
- (c)
Non-renewal source of energy is also called non-convetional source of energy.
- (d)
Coal, lignite, natural gas, crude petroleum oil, uranium etc. are renewable sources of energy.
Which one of the following is an intensive property?
- (a)
enthalpy
- (b)
mass
- (c)
temperature
- (d)
volume
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
Enthalpy of an element in its standard state at 25\(?\) and 1 atm pressure is always
- (a)
zero
- (b)
positive
- (c)
negative
- (d)
maximum
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
The molar heats of combustion of C2H4(g), C (graphite) and H2(g) are 310.62 kcal, 94.05 kcal and 68.32 kcal, respectively. The standard heat of formation of C2H4(g) would be
- (a)
+ 108.4 kcal
- (b)
- 54.2 kcal
- (c)
+ 54.2 kcal
- (d)
- 108.4 kcal
The standard heat of formation of water and heats of combustion of acetylene and ethylene are - 68.3 kcal, - 310.6 kcal and - 337.2 kcal respectively. The heat of reaction for the hydrogenation of acetylene at constant volume and (25oC) would be
- (a)
- 44.40 kcal
- (b)
+ 41.10 kcal
- (c)
- 41.7 kcal
- (d)
+ 41.7 kcal
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
Which one of the following statements is false?
- (a)
Work is a state function
- (b)
Temperature is a state function
- (c)
Change in the state is completely defined when the initial and final states are specified.
- (d)
Work appears at the boundary of the system
In thermodynamics a process is called reversible when
- (a)
surroundings and system change into each other
- (b)
there is no boundary between system and surroundings
- (c)
the surroundings are always in equilibrium with the system
- (d)
the system changes into the surroundings spontaneously
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
H2 + Cl2 \(\rightarrow\) 2HCl, \(\Delta\)H = 194 kJ. In this reaction heat of formation of HCl in kJ is
- (a)
- 194 kJ
- (b)
- 97 kJ
- (c)
+ 97 kJ
- (d)
+ 194 kJ
For the process : dry ice \(\rightarrow\) CO2(g)
- (a)
\(\Delta\)H is -ve while \(\Delta\)\(\rho \) +ve.
- (b)
both \(\Delta\)H and \(\Delta\)\(\rho \) are +ve.
- (c)
both \(\Delta\)H and \(\Delta\)\(\rho \) are -ve.
- (d)
\(\Delta\)H is +ve while \(\Delta\)\(\rho \) is negative.
\({ H }_{ 2 }(g)+{ Cl }_{ 2 }(g)\rightarrow 2HCl;\Delta H=-44?.\)
\(2Na(s)+2HCl(g)\rightarrow 2NaCl(s)+{ H }_{ 2 }(g);\Delta H=-152?.\)
For the reaction \(Na(s)+1/2{ Cl }_{ 2 }(g)\rightarrow NaCl(s)\), \(\Delta H\) = ?
- (a)
54 kcal
- (b)
- 98 kcal
- (c)
- 196 kcal
- (d)
- 108 kcal
The amount of work obtained in the isothermal reversible expansion of 20 g of argon at 27\(^oC\) from a pressure of 4 atm to 1 atm would be
- (a)
16.08 lit atm
- (b)
17.08 lit atm
- (c)
18.08 lit atm
- (d)
19.08 lit atm
An exothermic reaction is one in which the reacting substances
- (a)
have more energy than the products
- (b)
have less energy than the products
- (c)
have the same energy as the products
- (d)
are at a higher temperature than the products
\({ H }_{ 2 }+1/2{ O }_{ 2 }\rightarrow { H }_{ 2 }O;{ \Delta H }^{ o }=-68?.\)\(K+{ H }_{ 2 }O+aq\rightarrow KOH(aq)+1/2{ H }_{ 2 };{ \Delta H }^{ o }=-48?.\)\(KOH+aq\rightarrow KOH(aq)+1/2{ H }_{ 2 };{ \Delta H }^{ o }=-14?.\) For the above data, the standard heat of formation of KOH in kcal is :
- (a)
- 68 + 48 - 14
- (b)
- 68 - 48 + 14
- (c)
68 - 48 + 14
- (d)
68 + 48 + 14
For a system in equilibrium, \(\Delta\)G = 0, under conditions of constant
- (a)
temperature and pressure
- (b)
temperature and volume
- (c)
pressure and volume
- (d)
energy and volume
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
Which of the following equations represents standard heat of formation of methene?
- (a)
C (diamond) + 2H2 (g) \(\rightarrow\) CH4(g)
- (b)
C (graphite) + 2H2 (g) \(\rightarrow\) CH4(g)
- (c)
C (diamond) + 4H (g) \(\rightarrow\) CH4(g)
- (d)
C (graphite) + 4H (g) \(\rightarrow\) CH4(g)
For a process to be spontaneous
- (a)
the entropy of the system must increse
- (b)
the entropy of the surroundings must increse
- (c)
the entropy of the surroundings must decrese
- (d)
the entropy of the universe must increse
The molar enthalpy of formation of CO2 is equal to
- (a)
zero
- (b)
molar heat of combustion of diamond
- (c)
the sum of molar enthalpies of formation CO(g) and O2(g)
- (d)
the molar heat of combustion of CO(g).
A gas expands isothermally and reversibly. The work done by the gas is
- (a)
maximum
- (b)
minimum
- (c)
zero
- (d)
cannot be determined
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.