UNIT#08 THERMOCHEMSITRY AND ENERGETICS OF CHEMICAL REACTIONS Flashcards
(429 cards)
1
Q
Thermodynamics does NOT deal with:
A
➡Heat of Reaction❌
➡Rate of Reaction✅
➡Spontaneity of Reaction❌
➡Entropy of Reaction❌
2
Q
If an endothermic reaction is allowed to take place very rapidly in air, the temperature of the surrounding air will:
A
Decrease
3
Q
The exothermic process is;
A
Respiration
4
Q
A process, which takes place on its own without any outside assistance, is termed as:
A
Spontaneous
5
Q
The work done by expansion of gas against constant pressure is:
A
-PΔV
(Work done by the system is considered negative)
6
Q
A state function which describes together the internal energy and product of pressure and volume is called:
A
Enthalpy
7
Q
The enthalpy of formation of a compound is:
A
Either positive or negative
8
Q
Enthalpy is an expression for the:
A
Heat Energy
9
Q
Which one of the following has a standard enthalpy of formation that is zero?
A
Cu (s)
➡Standard Enthalpy of an element in its standard state is zero
10
Q
Which of the following statement is correct:
A
➡ΔH is positive for exothermic reaction❌
➡ΔH is negative for endothermic reaction❌
➡The heat of neutralization of strong acid with a strong base is always the same✅
➡The enthalpy of fusion is negative❌
11
Q
What is not correct about ΔHf :
A
➡Its value gives an idea about the relative stability of reactants and the products❌
➡It is always negative❌
➡Value depends upon the nature of bonds✅
➡ITs value may be negative or positive❌
12
Q
Which of the following has a positive value of enthalpy:
A
Atomization
13
Q
NaOH + HCl ➡ NaCl + H2O
Enthalpy change in the above reaction is called:
A
Enthalpy of neutralization
14
Q
Enthalpy o neutralization per mole of H2SO4/Ba(OH)2 is:
A
-54.7 kJmol-1
15
Q
Which of the following processes has always ΔH= -ve
A
Combustion
16
Q
Heat absorbed or evolved during the chemical reaction at constant pressure is:
A
ΔH
17
Q
The change in enthalpy of a system when one mole of the substance is completely burnt in air or oxygen is called:
A
Heat of combustion
18
Q
Which of the following enthalpy change may be positive or negative value:
A
➡ΔHc
➡ΔHsolution
19
Q
Neutralization of acid-base is:
A
➡Spontaneous
➡Exothermic
20
Q
ΔH represent the enthalpy change at;
A
25°C and 1 atm pressure
21
Q
The enthalpy changes ΔH of a process are given by the relation:
A
ΔE = ΔH + PΔV
22
Q
A system absorbs 100kJ heat and performs 50kJ work on the surroundings. The change in internal energy of the system is:
A
50kJ
23
Q
Which equation represents the atomization of iodine:
A
1/2 I2(s) ➡ I(l)
24
Q
The ΔH of a reaction is recorded at:
A
298K
25
Which of the following enthalpies is always negative;
Enthalpy of neutralization
26
Which of the following enthalpies is always positive:
Enthalpy of sublimation
27
Enthalpy of reaction can be measured in;
Glass calorimeter
28
How much heat is evolved by 100g of water when its temperature decreases from 25°C to 5°C?
-84,00J
(q = msΔT)
➡Specific Heat o water is 4.2 J/gK
29
Enthalpy of combustion of food, fuel and other compounds can be measured accurately by
Bomb Calorimeter
30
Which enthalpy of reaction can not be determined by glass calorimeter
Enthalpy of combustion
31
Total Heat energy (q) can be calculated in a bomb calorimeter by using the following:
c x ΔT
(q = c x ΔT)
32
Which one of the following is applied to calculate lattice energy indirectly?
Born-Haber cycle
33
In order to determine ΔHlattice of ionic compound which is the correct relationship?
ΔHlattice = ΔHf - ΔHx
34
Which equation shows the lattice energy of an ionic compound?
ΔH (lattice) = Hf - Hx
35
With the increase in charge to size ratio of ions, the lattice energy:
Increases
(ΔHlattice ∝ Charge/Size of an atom)
36
Hess's law is analogous to;
Law of heat summation
37
Which of the following enthalpies of formation cannot be measured directly?
➡ΔH lattice for the ionic compound
➡ΔH for CO
➡ΔH for B2O3
38
The standard enthalpy changes of formation of carbon dioxide and water are -394kJmol-1 and -286kJmol-1 respectively, if the standard enthalpy change of combustion of propyne, C3H4 is -1932kJmol-1. What is the standard enthalpy change of formation?
-184 kJmol-1
39
The heat of combustion o ethane (C2H6) is -337.0 kcal at 25°C. The heat reaction when 3g of ethane is burnt completely is:
-33.7 kcal
40
Hess's law is known as:
Law of heat summation
41
Relation between qp and qv:
qp > qv
42
The formation of SO3 from SO2 is ___ reaction.
Endothermic
43
For strong acid and strong base neutralization energy:
Constant
44
Unit of energy:
➡Joule
➡Kilojoule
➡Calorie
45
The unavailability of methods to find out the heat of reactions accurately makes thermochemistry
A limited field of study
46
Which one of the following is not an example of a state function?
Heat (q)
47
Temperature and volume in an experiment are part of :
State of a system
48
In endothermic reaction heat is absorbed from:
Surrounding
49
ΔH for the exothermic reaction is:
Negative
50
Which of the following condition is constant in the bomb calorimeter;
Volume
51
Heat exchanged between the system and surrounding at constant volume is shown by the relation
ΔH = qv + w
52
At constant volume, the heat supplied is equal to:
Internal energy change
53
Work done on the system is:
Positive
54
Which one is not a state function:
Work
55
Heat supplied at constant pressure equals:
Enthalpy
56
Enthalpy is the sum of the internal energy and:
Work done
57
Heat o a solution for the substance whose solubility decreases with an increase in temperature is:
Negative
58
Enthalpy change of solution of Na2CO2 is a ____ reaction
Exothermic reaction
59
An enthalpy cycle used to calculate the lattice energy is;
Born Haber cycle
60
Energy for the endothermic reaction is given a ___ value:
Positive
61
Which is correct for 1st law of thermodynamics?
ΔE = q +W
62
The energy of products is greater in:
Endothermic Reaction
63
Amount of heat absorbed by 2kg of water when temperature changes by 10°C are:
84,000
(q = msΔT)
64
When a bond is formed, energy is;
Released
65
Which one is the state function?
PTVUHSG
66
What is the value of one calorie in Joule?
4.18J
67
The formation of carbon dioxide hinders calculating the heat of formation of;
CO
68
Decomposition of water into hydrogen and oxygen is a:
Endothermic Reaction
69
The heat of the formation of CO
-110 kJ/mol
70
When 40J heat is provided and 20J work is done, if the initial energy is 10J then the final internal energy is;
30J
71
In glass calorimeter, which is constant
Pressure
72
A spontaneous process is;
➡Unidirectional and Irreversible
➡Unidirectional and Real
➡Irreversible and Real
73
ΔH will be given a negative sign in:
Exothermic Reaction
74
Reactants have high energy than products;
Exothermic Reaction
75
The reaction of water with quick lime results in a rise in the temperature of the system. Using the concentration change, indicate the nature of reaction.
Exothermic Reaction
76
Which of the following enthalpy change is always exothermic?
Enthalpy of Combustion
77
The heat of formation of MgO is given below.
Mg + 1/2 O2 ➡MgO ΔH=-692 kJ/mol. This equation shows that:
The product is very stable
78
When one mole of gaseous hydrogen ions are dissolved in water to form an infinitely dilute solution, the amount of heat liberated is;
-1075 kJ/mol
79
In standard enthalpy of atomization heat of surrounding:
Decreases
80
The heat of formation (ΔH) for CO2 is;
-394 kJ/mol
81
2H2 + O2 ➡2H2O ΔH=205.5 kJ/mol
What will be the enthalpy change in the above reaction:
-205.5 kJ/mol
82
1/2 H2(g) ➡ H(g) ΔH=218 kJ/mol
In this reaction ΔH will be called:
Enthalpy of atomization
83
Determine the value of enthalpy of formation of NH4Cl:
-692 kJmol-1
84
Enthalpy is measured at:
298K and 1 atm
85
When two moles of H2 and one mole of O2 react to form H2O 484 KJ heat is evolved what is ΔHf for one mole of H2O
-242 KJmol-1
86
The lattice energy of an ionic crystal is the enthalpy of
Formation
87
The thermal energy at constant pressure is called:
Enthalpy
88
The born-Haber cycle is used to determine the lattice energies of;
Ionic Solids
89
One calorie is equal to;
4.18J
90
The net change in energy in a chemical reaction is the same whether it takes place directly or indirectly. It is called:
Hess's Law
91
The enthalpy of formation of an ionic compound is -392kJ/mol. Total energy changes (ΔHx) involved in the formation of gaseous ions from normal physical state is 280kJ/mol. The enthalpy of lattice is:
-672 kJ/mol
92
Enthalpy of neutralization of strong acids and bases is same because:
H+ and OH- combine to form H2O
93
Unit of heat is SI system is:
J
94
If there is the interconversion of solid and liquid states then:
➡ΔV = 0
➡ΔH = ΔE
95
First law of thermodynamics relates:
➡Internal Energy
➡Heat
➡Work
96
An exothermic process is:
O (g) + 1e- ➡O-1
97
If an endothermic reaction is allowed to take place very rapidly in air the temperature of the surrounding air:
Decreases
98
Which of the following sets constitutes of all the state functions of system:
➡Enthalpy
➡Entropy
➡Internal Energy
99
___ is not a state function.
Heat
100
Which of the following enthalpy change (ΔH) is always endothermic
ΔH (atomization)
101
Incorrect statement about endothermic reaction is;
➡Evaporation is an endothermic process❌
➡Products are more stable than reactants✅
➡ΔH is positive❌
➡Reaction mixture becomes stable❌
102
Among the following changes, which is exothermic?
➡Freezing
➡Condensation
➡Combustion
103
Which of the following process will be spontaneous and endothermic:
➡Melting of ice
➡Evaporation of water
➡Dissolution of NH4Cl
104
When water is added to quicklime, the reaction is:
Explosive
105
Which is non-spontaneous reaction?
N2 + O2 ➡2NO
106
The sum of all the energies of atoms, molecules or ions within a system is called:
Internal Energy
107
Which statement is true when liquid is converted into vapors?
Heat is absorbed
108
When ΔE of a system increases, then which of the following possibilities is correct?
➡Temperature of the system can increase
➡Phase change may take place
➡Chemical reaction can occur
109
ΔH = ΔE for which of the following reaction
K + H2O ➡ KOH + H2
110
According to the first law of thermodynamics, energy from the system to the surrounding can be transferred in the form of:
Heat and Work
111
Change in enthalpy of ΔH of a gaseous system can be calculated by following relationship:
ΔH = ΔE + PΔV
112
The amount of heat evolved when one mole of CH3COOH reacts with one mole of NaOH is:
< 57.4 kJ
113
Standard enthalpies of formation of O3, CO2, NH3 and HI are 142.2, -33.3, -46.2 and +25.9 kJ/mol respectively. The order o their increasing stabilities will be:
O3, HI, NH3, CO2
114
The enthalpy change for the reaction C(s) + O2(g) ➡ CO2 is called:
➡Enthalpy of formation
➡Enthalpy of combustions
➡Enthalpy of reaction
115
Which of the following processes has always ΔH = -ve
Combustion
116
Which one of the following reactions represents both standard enthalpy of combustion as well as standard enthalpy of formation
C (s) + O2 ➡ CO2(g)
117
The enthalpy of atomization of H2 is 218kJ/mole, the enthalpy of formation of H2 from gaseous atoms:
-218 kJ/mole
118
Which reaction shows enthalpy of formation:
C + O2 ➡CO2
119
The enthalpy of formation of an ionic compound is -392 kJ/mol. Total energy changes involved in the formation of gaseous ions form normal physical state is 280 kJ/mol. The enthalpy of lattice is:
-672 kJ/mol
120
Which of the following change in enthalpy in Born-Haber cycle may be negative
H (E.A)
121
Hess Law follows:
➡First law of thermodynamics
➡Law of conservation of energy
122
The net heat change in a chemical reaction is the same whether it is brought about in two or more different ways in one or several steps. It is known as:
Hess's Law
123
Standard heat of formation of Al2O3 cannot be determined directly because:
Protective layer of Al2O3 form
124
One joule is equivalent to:
1/4.184 Cal
125
The enthalpies of all elements in their standard states are;
Zero
126
____ is not a state function.
Heat
127
No work is done at constant:
V
128
For an endothermic reaction, enthalpy of reactants:
Is smaller than that of the products
129
Most of the reactions which give stable products are;
Exothermic
130
Decomposition of H2O is;
Endothermic reaction
131
What type of reaction constitutes a limiting case between spontaneous and non-spontaneous reactions:
Reversible Reaction
132
In an endothermic reaction:
Er < Ep
133
In an exothermic reaction the heat energy is ______ while in an endothermic reaction it is;
➡Released
➡Absorbed
134
Whenever a reaction is endothermic, then it means that:
Heat is transferred from the surroundings to the system
135
Enthalpy of neutralization of strong acids and strong bases have the same values because;
The net change involves the combination of H+ and OH- ions to form water
136
The measurement of enthalpy change at standard conditions means that we should manage the measurement at:
25°C at 1 atm
137
The enthalpy change for the reaction C2H2 + 5/2 O2 ➡2CO2 + H2O is known as enthalpy of:
Enthalpy of Combustion
138
BaCl2 + H2SO4 ➡ BaSO4 + HCl, an exothermic reaction, the heat change represented by the above equation is called;
Heat of Reaction
139
The enthalpy of atomization of H2 is 218 kJ/mol and the enthalpy of formation of H2 from gaseous atoms
-436 kJ/mol
140
An enthalpy change which is always exothermic:
ΔHn
(Enthalpy of Neutralization)
141
The enthalpy change for the reaction, C2H5OH + 3O2 ➡ 2CO2 + 3H2O is known as enthalpy of;
Combustion of C2H5Oh
142
Which of the following gases have the highest heat of combustion
Acetylene
143
Which one of the following pairs has a maximum enthalpy of neutralization;
HCl + NaOH
144
ΔH of a system can be calculated by which of the following relationship
q = m x s x ΔT
145
Bomb calorimeter is used to determine the;
ΔHc
146
What is the unit of molar heat capacity?
J/mol¹K¹
147
This is true about the lattice energy of an ionic compound
➡Cannpt be determined directly
➡Can be obtained by means of the Born Haber cycle
148
The enthalpy of formation of an ionic compound is -392 kJ/mol. Total energy changes (ΔHx) involved in the formation of gaseous ions from a normal physical state is 280 kJ/mol. The enthalpy of the lattice is;
-672 kJ/mol
149
Choose from the following the correct statement about the Born Haber cycle
The lattice energy of crystalline substances can be calculated easily
150
Standard heat of formation of Al2O3 cannot be determined directly because:
A protective layer of Al2O3
151
The heat of combustion of graphite at 25°C is -393.51 kJ/ mol and that of a diamond is -395.41 kJ/mol. What is the enthalpy for the conversion of graphite into diamond at the same temperature?
+1.9 kJ/mol
152
By applying Hess's Law, we can calculate:
ΔH
153
Enthalpy of neutralization of strong acids and strong bases have the same values because:
The net change involves the combination of H+ and OH- ions to form water.
154
For an endothermic reaction, enthalpy of reactants
Is smaller than that of the products
155
Which of the following has a positive value of enthalpy
Atomization
156
The net heat change in a chemical reaction is the same whether it is brought about in two or more different ways in one or several steps. It is known as;
Hess's Law
157
Hess's Law is analogous to;
Law of Heat summation
158
NaOH + HCl ➡NaCl + H2O. Enthalpy change in the above reaction is called;
ΔH = ΔE
159
A calorie is equivalent to:
4.184 J
160
The values of ΔH for the process I + e ➡ I-1 are;
< O
161
The enthalpy of formation of a compound is;
Either Positive or Negative
162
What is correct about the heat of combustion:
It is always negative
163
What is not correct about ΔHf:
It is always negative
164
If an endothermic reaction is allowed to take place very rapidly in air, the temperature of the surrounding air will;
Decrease
165
One Joule is equivalent to:
1/4.184 cal
166
The heat of reaction depends upon:
➡Temperature of the Reaction
➡Physical states of the reactants and the products
167
The exothermic process is;
Respiration
168
During an exothermic or endothermic reaction, one of the following formulas is used to calculate the amount of heat evolved or absorbed:
q = m x s x ΔT
169
Most of the reactions which give stable products are;
Exothermic
170
The measurement of enthalpy change at standard conditions means that we should manage the measurement at:
25°C at 1 atm
171
The total heat content of a system is called:
Enthalpy
172
The enthalpies of all elements in their standard states are;
Zero
173
A state function which describes together the internal energy and product of pressure and volume is called
Enthalpy
174
The enthalpy change for the reaction C2H2 + 5/2 O2 ➡ 2CO2 + H2O is known as enthalpy of;
Combustion of C2H2
175
The value of ΔV is very small. The term PΔV can be neglected for processes involving:
➡Liquid
➡Solid
176
The lattice energy of NaCl is;
-787 kJ/mol
177
Decomposition of H2O is :
Endothermic Reaction
178
According to Hess's Law, the enthalpy change for a reaction:
independent of the path
179
Enthalpy of formation of one mole of ionic compound form gaseous ion under standard condition is called;
Lattice Energy
180
Change in enthalpy (ΔH) of a system can be calculated as;
ΔH = ΔE + PΔV
181
If the internal energy of the system is increased:
➡Change in the state of the system may occur
➡Temperature of the system may rise
➡Chemical reaction may take place
182
Enthalpy of a reaction can be measured by:
Glass calorimeter
183
In order to determine ΔH of ionic compound which is the correct relationship:
ΔH (Lattice) = ΔHf - ΔHx
184
Enthalpy of neutralization per mole of H2SO4/ Ba(OH)2 is;
-57.4 kJ/mol
185
Whenever a reaction is endothermic, then it means that ;
Heat is transferred from the surroundings to the system
186
How much heat is absorbed by 100g of water when its temperature decreases from 25°C to 5°C
(Heat capacity is 4.2 k/gK)
-84,00 J
187
One of the best applications of Hess's law to calculate the lattice energy of ionic compound is;
Born-Haber Cycle
188
ΔH of a system can be calculated by which of the following relationships:
q = m x s x ΔT
189
Which of the following processes has always ΔH= -ve
Dissolution of an ionic compound
190
ΔH = ΔE is true for which of the following reaction?
▶K + H2O ➡ KOH + H2❌
▶N2 + 3H2 ➡ 2NH3❌
▶AlCl3 + 3NaOH ➡ Al(OH)3 + 3NaCl✅
▶ 4Na + O2 ➡ 2Na2O❌
191
BaCl + H2SO4 ➡ BaSO4 + HCl ΔH =-22.4 kJ/mol, the heat change represented by the above equation is called;
The heat of the reaction of BaSO4
192
When water is added to quick lime, the reaction is:
Exothermic
193
What type of reaction constitutes a limiting case between spontaneous and non-spontaneous reactions;
Reversible Reaction
194
Thermodynamics does NOT deal with
Rate of Reaction
195
____ is not a state function.
Heat
196
The enthalpy of atomization of H2 is 218 kJ/mole and the enthalpy of formation of H2 from gaseous atoms:
-436 kJ/mol
197
The enthalpy change for the reaction C + O2 ➡ CO2 is called:
➡Enthalpy of formation
➡Enthalpy of reaction
➡Enthalpy of combustion
198
Which equation shows lattice energy for the ionic compound?
Na+ + Cl- ➡NaCl
199
A process which is spontaneous and endothermic;
H2O(l) ➡ H2O(g)
200
An enthalpy change which is always exothermic
ΔHn
201
All of the following are exothermic processes except:
Evaporation
202
Enthalpy of combustion of food, fuel and other compounds can be measured accurately by:
Bomb Calorimeter
203
The enthalpy of formation of an ionic compound is -392 kJ/mol. Total energy changes (ΔH) involved in the formation of gaseous ions from the normal physical state is 280 kJ/mol. The enthalpy of the lattice is;
-672 kJ/mol
204
Which of the following enthalpies of formation cannot be measured directly:
➡ΔH(lattice) of an ionic compound
➡ΔHf for CO
➡ΔHf for B2O3
205
All are slow processes except:
The reaction of AgNO3 with NaCl
206
Heat absorbed or evolved during the chemical reaction at constant pressure is;
ΔH
207
A bomb calorimeter is used to determine the:
ΔHc
208
Which enthalpy of reaction can not be determined by glass calorimeter
Enthalpy of combustion
209
Which is not related to state function:
➡It deals with atomic level✅
➡It is a macroscopic property❌
➡It depends upon initial and final values❌
➡It is independent on apth❌
210
In an endothermic reaction:
Er < Ep
211
Standard heat of formation of Al2O3 cannot be determined directly because:
Protective Layer of Al2O3
212
In an exothermic reaction, the heat energy is ___ while in an endothermic reaction it is___
➡Released
➡Absorbed
213
Which one is the endothermic and spontaneous process
Melting of Ice
214
One kilo calorie is equal to;
4184 J
215
By convention, the standard heat of formation of all elements is assumed to be:
Zero
216
The change in enthalpy of a system when one mole of the substance is completely burnt in excess of air or oxygen is called:
Heat of combustion
217
Which of the following enthalpy change always have a negative value:
ΔHc
218
The change in enthalpy when one mole of a substance is dissolved in a specified quantity of solvent at a given temperature is called:
Heat of Solvation
219
Neutralization of acid-base is;
➡Spontaneous
➡Non-Spontaneous
220
The born-Haber cycle is an application of;
Hess's law
221
ΔH represent the enthalpy change at;
25°C and 1 atm pressure
222
The enthalpy change ΔH of a process is given by the relation:
ΔH = ΔE + PΔV
223
A system absorbs 100 kJ heat and performs 50kJ work on the surroundings. the increase in internal energy of the system is:
50K
224
Which equation represents the atomization of iodine ;
1/2 I2 (s) ➡I (g)
225
The heat of combustion of ethane is -337.0 kcal at 25°C. The heat of the reaction when 3g of ethane is burnt completely is;
-33.7 kcal
226
The heat of combustion of graphite at 25°C is 393.51 kJ/mol ad that of a diamond is 395.41 kJ/mol. What is the enthalpy for the conversion of graphite into diamond at the same temperature?
+1.9 kJ/mol
227
The standard enthalpy changes of the formation of carbon dioxide and water are -394kJ/mol and -286 kJ/mol respectively, if the standard enthalpy change of combustion of propyne, C3H4 is -1938 kJ/mol. What is its standard enthalpy change of formation?
-184 kJ/mol
228
Total heat energy (q) can be calculated in a bomb calorimeter by using the following formula:
c x ΔT
229
Enthalpy of neutralization of strong acids and strong bases have same values of because:
The net change involves the combination of H+ and OH- ions to form water
230
For endothermic reaction, enthalpy of reactions:
Is smaller than that of the products
231
Which of the following has positive value of enthalpy:
Atomization
232
The net heat change in a chemical reaction is the same whether it is brought about in two or more different ways in one or several steps. It is known as:
Hess's Law
233
Hess's law is analogus to:
Law of heat summation
234
NaOH + HCl ➡NaCl + H2O.
Enthalpy change in the above reaction is called
Enthalpy of neutralization
235
If a reaction involves only solids and liquids, which of the following is true?
ΔH = ΔE
236
Calorie is equivalent to:
4.184 J
237
The values of ΔH or the process I(g) + e- ➡I-1 is :
<0
238
The enthalpy of formation of a compound is:
Either positive or negative
239
What is correct about heat of combustion:
It is always negative
240
What is not correct about ΔH:
➡ It is always negative✅
➡ Its value is gives an idea about the realtive stability of reactants and products❌
➡ Value depends upon nature of bonds❌
➡ Its value can be greater or less than zero❌
241
If an endothermic reaction is allowed to take place very rapidly in air, the temperature of the surrounding air will:
Decrease
242
One Joule is equivalent to:
1/4.184 cal
243
The heat of reaction depends upon
➡Temperature of the reactants
➡Physical States of the reactants and the products
244
The exothermic process is:
Respiration
245
During an exothermic process or endothermic reaction one of the following formulas is used to calculate the amount of heat evolved or absorbed:
q = m x s x ΔT
246
Most of the reactions which give stable products are
Exothermic
247
The measurement of enthalpy change at standard conditions means that we should manage the measurement at;
25°C at 1 atm
248
Total heat content of a system is called:
Enthalpy
249
The enthalpies of all elements in their standard states are:
Zero
250
A state function which describees together the internal energy and product of pressure and volume is called;
Enthalpy
251
The enthalpy change for the reaction C2H2 + 5/2 O2 ➡2CO2 +H2O. is known as the enthalpy of:
COmbustion of C2H2
252
The value of ΔV being very small. The term PΔV can be neglected for process involving:
➡Liquid
➡Solid
253
The lattice energy of NaCl is:
-787 kJ/mole
254
Decomposition of H2O is :
Endothermic reaction
255
According to Hess's law ,the enthalpy change for a reaction:
Independent of the path
256
Enthalpyof formaton of one mole of ionic compound form gaseous ion under standard condition is called:
Bond Energy
257
Choose from the followings the correct statements about Born Haber cycle:
The energy changes in a cyclic process is not zero
258
Change in enthalpy (ΔH) of a system can be calculated by:
ΔH = ΔE + PΔV
259
If internal energy of the system is increased:
➡Change in state of the system may occur
➡Temperature of the system may rise
➡Chemical reaction may take place
260
Enthalpy of a reaction can be measured by:
Glass Calorimeter
261
To determine ΔH of ionic compound which is the correct relationship
ΔH (lattice) = Hf - Hx
262
Enthalpy of neutralization per mole of H2SO4/ Ba(OH)2 is:
-57.4 kJ/mole
263
Whenever a reaction is endothermic , then it means that:
Heat is transferred from the surroundings to the system
264
How much heat is abosrbed by 100g of water when ts temperature decreases from 25°C to 5°C?
(Heat capacity of H2O=4.2 J/gK)
-84,00J
265
One of the best applications of Hess's law to calculate the lattice energy of ionic compound is:
Born Haber Cycle
266
ΔH of a system can be calculated by which of the following relationship:
q = m x s x ΔT
267
Which of the following processes has always ΔH=-ve
Dissolution of ionic compound
268
ΔH=ΔE is true for which of the following reaction:
AlCl3 + 3NaOH ➡Al(OH)3 + 3NaCl
269
When water is added to quicklime, the reaction is;
Exothermic
270
ΔH = ΔE for which of the folowing reaction:
AlCl3 + 3NaOH ➡Al(OH)3 + 3NaCl
271
What type of reaction constitute a limiting case between spontaneous and non-spontaneous reaction:
Reversible Reaction
272
Thermodynamics does NOT deal with:
Rate of reaction
273
____ is not a state function:
Heat
274
The enthalpy of atomization of H2 is 218 kJ/mole, the enthalpy of formation of H2 from gaseous atoms
-436 kJ/mole
275
The enthalpy of change for the reaction C + O2 ➡CO2 is called:
➡Enthalpy of formation
➡Enthalpy of reaction
➡Enthalpy of combustion
276
Which equation shows lattice energy of ionic compound:
Na+(g) + Cl-(g) ➡NaCl
277
A process which is spontaneous and endothermic:
H2O (l) ➡H2O(g)
278
An enthalpy change which is always exothermic:
ΔH n
279
All of the following are exothermic process except:
➡Freezing of water❌
➡Evaporation✅
➡Condensation❌
➡Combustion❌
280
Enthalpy of combustion of food, fuel and other compounds can be measured accurately by:
Bomb calorimeter
281
The enthalpy of formation of ionic compound is -392 kJ/mol. Total energy changes (ΔHx) involved in the formaton of gaseous ions from normal physical state is 280 kJ/mol. The enthalpy of lattice (ΔHlattice) is:
-672 kJ/mole
282
Which of the following enthalpies of formation cannot be calculated directly:
➡ΔH(lattice) for ionic compounds
➡ΔHf for CO
➡ΔHf for B2O3
283
All are slow procecsses except:
Reacton of AgNO3 with NaCl
284
Heat absorbed or evolved during the chemical reaction at constant pressure is:
ΔH
285
A bomb calorimeter is used to determine the:
ΔHc
286
Which enthalpy of reaction cannot be determined by glass calorimeter:
Enthalpy of combustion
287
Which is not related to state function:
It deals with atomic level
288
In an endothermic reaction :
Er < Ep
289
Standard heat of formation of Al2O3 cannot be determined directly because:
Protective layer of Al2O3
290
In an exothermic reaction, the heat energy is __- while in endothermic reaction it is;
Released, Abosrboed
291
Which one is endothmeric and spontaneous process:
Melting of ice
292
One kilo calorie is equal to
4184 J
293
By convention, the standard heat of formation of all elements is assumed to be:
Zero
294
The change in enthalpy of a system when one mole of the substance is compeltely burnt in excess of air or oxygen is called:
Heat of combustion
295
Which of the following enthalpy change always have a negative value:
ΔHc
296
The change in enthalpy when one mole of a substance is dissovled in a specified quantity of solvent at a given a temperature is called:
Heat of solvation
297
Neutralization of acid-base is;
➡Spontaneous
➡Exothermic
298
Born Haber cycel is an applicaton of;
Hess's Law
299
ΔH represent the enthalpy change at;
25°C and 1 atm pressure
300
The enthalpy change of ΔH of a process is given by the realtion:
ΔH = ΔE + PΔV
301
A system absrobs 100 kJ heat and perorms 50KJ work on the surroundngs. The increase in internal energy of the system is:
50kJ
302
Which equaton represents the atomization of iodine:
1/2 I2 (s) ➡I(s)
303
The heat of combustion of ethane (C2H6) is -337.0 kcal at 25°C. The heat of the reaction when 3g of ethane is burnt completely is:
-33.7 kcal
304
Heat of combustion of graphite at 25°C is -393.51 Kj/mol and that of diamond is -395.41 kJ/mol. What is the enthalpy for the conversion of graphite into diamond at same temperature.
+1.9 kJ/mol
305
The standard enthalpy changes of formation of carbon dioxide and water are -394 kJ/mol and -286 kJ/mole respectively, if the standard enthalpy change of combustion of propyne, C3H4 is -138 kJ/mole. What is its standard enthalpy change of formaton?
-184 kJ/mole
306
Total energy (q) can be calcualted in a bomb calorimeter by using following ormula:
c x ΔT
307
One calorie is equal to:
4.184 J
308
Which of the following change in enthalpy in Born-Haber cycle may be negative:
ΔH (E.A)
309
Which of the following is incorrect about enthalpy of neutralization?
➡Its maximum value is 57.5 kJ/mol❌
➡It is equal to enthalpy of formation of water from ions❌
➡It is less than 57.5 kJ/mol when one o the acid or base is weaker❌
➡Energy is abosrbed in this process✅
310
Standard enthalpy of Al2O3 cannot be measured because:
Protective layer of oxide covers the surface
311
The dissolution of ammonium chloride in water is a/an:
➡Endothermic process
➡Spontaneous process
312
For an endothermic reaction the value of ΔH is denoted by:
Positive sign
313
Which is used to measure enthalpy of combustion:
Bomb calorimeter
314
For a given process, the heat change at constant pressure (qp) and constant volume (qv) are related to each other as:
qp > qv
315
The amount o heat required to convert one mole of a solid directly into its vapour state at STP is called as
Standard heat of sublimation
316
Enthalpy of neutralization of all the strong acids and strong bases has the same value because:
The net chemical change involves the combination o H+ and OH- ions to form water
317
In endothermic reactions, the heat contents of the:
Product is more than that of reactant
318
Work may be defined in terms of pressure-volumes s:
1 atm 298K
319
Which of the following molecule show only translational motion?
He
(Mono-atomic)
320
The study of heat changes accompanied by a chemical reaction is called as:
Thermochemistry
321
The system becomes more stable if it:
Loses energy
322
According to the first law of thermodynamics energy from the system to the surroundings can be transferred in the form of:
Heat and Work
323
The sum of all the energies of atoms, molecules, or ions within a system s called:
Internal Energy
324
Evaporation of water is ___ change.
Endothermic
325
The expresson ΔE=q + w is:
First law of thermodynamics
326
An enthalpy change which is always endothermic
ΔH (atomization)
327
The enthalpy change in a cyclic process is:
Zero
328
The net heat change in a chmical reaction is same whether it is brought in two or more diferent ways n one or several steps. it is known as:
Hess's law
329
Which of the following is correct relation at constant pressure
ΔH = qp
330
Which of the following is the correct representation for the calculation of lattice energy
ΔHf = ΔHx + ΔHl
331
The enthalpy of neutralization for given reaction
H2SO4 + Ba(OH)2 ➡BaSO4 + 2H2O
-57.4 kJ/mol
332
The change in enthalpy of a system when one mole of the substance is completely burnt in excess of air or oxygen is called:
Enthalpy of combustion
333
ΔH represent the enthalpy change at:
➡25°
➡1 atm pressure
334
A system absorbs 100 kJ heat and performs 50 kJ work. The increase in internal energy of the system is:
50 kJ
335
Which of the followig enthalpy is always proceeding through evolution of heat?
Enthalpy of combustion
336
In order to determine ΔH (lattice) of ionic compound which is correct relatonship:
ΔH (lattice) = ΔHf - ΔHx
337
With decrease in charge to size ratio of ions, the lattice energy:
Decrease
338
Hess's law is analogus to:
Law of constant heat summation
339
The heat of combustion o ethane (C2H6) is -337.0 kJ at 25°C. The heat of the reaction when 3g of ethane is burnt completely is:
-33.7 kJ
340
Born Haver cycle is an application of:
Hess's Law
341
Which of the following enthalpy of formation cannot be measured directly?
➡ΔH (lattice) for ionic compound
➡ΔHf of CO
➡ΔHf of B2O3
342
Enthalpy of combustion of food, fuel and other compounds can be measrued accurately by:
Bomb calorimeter
343
Which equation shows lattice energy for ionic compound
Na+(g) + Cl-(g) ➡NaCl (s)
344
A process which is spontaneous and endothermic
H2O (l) ➡ H2O (g)
345
The enthalpy change for the reaction C(s) + O2 (g) ➡CO2 (g) is called:
➡Enthalpy of formaton of CO2
➡Enthalpy of combustion of C
➡Enthalpy of reaction
346
For a given gaseous process, the heat changes at constant pressure (qp) and at constant volume (qv) are related to each other as
qp > qv
347
The enthalpy of formation of an ionic compound is -390 kJ/mol. Total energy changes (ΔHx) involved in the fomration of gaseous ions from normal physical state is 280 kj/mol. The enthalpy of lattice (ΔH lattic.) s;
-670 kJ/mol
348
Which one indicates enthalpy of atomization
Na (s) ➡Na (g)
(Physical state to gaseous 1 mole)
349
The standard enthalpy of ormatio of all the elements in their standard physical state is:
Zero
350
Does no depend on initial and final state;
Heat
351
Enthalpy of formation of hydroge molecule is -436 kJ/mol. What will be enthalpy of atomization o fhydrogen.
+218 kJ/mol
(As atomization is for 1 mole)
352
he enthalpy change for the reaction, C2H2 + 5/2 O2 ➡2CO2 + H2O is known asenthalpy of:
Combustion o C2H2
353
Which of the following pairs has maximum enthalpy o neutralization?
HCl + NaOH
354
Amount of energy abosrbed when 1 mole of solid Na Cl is dissociated into its gaseous ions:
+787 kJ/mole
355
Calorie is equivalent to;
4.184 J
356
For the reaction NaCl (s) ➡Na+ (aq) + Cl- (aq) the change in enthalpy is called:
heat o solution
357
Evaporation of water is an exceptional case of:
Spontaneous
358
Which statement is contrary to the first all of thermodynamics?
Continuous production of mechanical work without supplying an equivalent amount of heat is possible
359
Born haber's cycle enables us to calculate:
Lattice Energy
360
Which statement is not correct about ΔH?
➡ΔH of the reaction depends on temperature❌
➡ΔH of reaction can > or < zero❌
➡ΔH of catalyzed and uncatalyzed reaction is same❌
➡ΔH is always < 0✅
361
Which of the following processes is always endothermic?
Atomization
362
Which one of the following statements is correct or the neutralizaton of a strong acid by a strong alkali in aqueous solution at 25°C?
The enthalpy change per mole of H2O formed is independent of the acid or alkali used as they are strong
363
According to Born Haber cycle, ΔH (lattice) of ionic compound is determined by the formula:
ΔH (lattice) = ΔHf - ΔHx
364
Lattice energy helps to explain all of the following properties of ionic compounds EXCEPT:
Dipole Moment
365
In azeotropic mixture showing positive deviation from Raoult's law, the volume of the mixture is:
Slightly more than the total volume of the components
366
All of the following reactions are exothermic EXCEPT:
N2(g) + O2(g) ➡2NO (g)
367
For which one of the following compounds standard enthalpy change (ΔH) can be measured directly by calorimeter?
MgO
368
All of the following are state functions EXCEPT?
q
369
All of the following standard enthalpy change (ΔH) have only positive value EXCEPT:
➡ΔHv❌
➡ΔHBDE❌
➡ΔHsol✅
➡ΔHi❌
370
12.0 g of graphite is burnt in a bomb calorimeter and the temperature is recorded in 5K. Calculate the enthalpy of combustion (ΔH) of graphite if the heat capacity of the calorimeter is 0.0 kJ/mol
-450 kJ/mol
371
A glass calorimeter is used to determine:
ΔH neutralization
372
If an endothermic reaction is allowed to take place very rapidly in the air, the temperature of the surrounding air:
Decreases
373
The nature of an aqueous solution of ammonia (NH3) is:
Basic
374
Internal energy of a system depends on all the factors EXCEPT
Path
375
Which of the following is a correct representation of the electron affinity of chlorine:
Cl (g) + 1e ➡Cl -1 (g) ΔH = -349 kJ/mole
376
Which value of heat of fomration indicates that the product is the least stable?
+ 64.8 kCal
377
Absorption of heat occurs when:
NH4Cl dissolved in water
378
Identify the state function among the following:
q + W
379
For the neutralization of 1 mole o H2SO4 with 2 moles of NaOH in dilute solution, the heat liberated is:
> 57 kJ
380
The enthalpy change of a reaction does not depend o:
Different intermediate reactions
381
Which enthalpy change (ΔH) is relevant in the following equation
H2 ➡ H + H ΔH=+436 kJ/mol
Bond Dissociation Energy
382
Heat of formation of MgO is given below:
Mg + 1/2 O2 ➡MgO ΔH = -692 kJ/mol
This equaton shows that :
The product is ver stable
383
In exothermic reaction heat transer from:
System to surrounding
384
Enthalpy change during the formation of one mole fo atoms from its elements is called enthalpy of atomization. The element in this change is n:
➡Solid State
➡Liquid State
➡Gaseosu State
385
Which of the following formula cannot be used in Hess’s law?
H (lattice) = Hf + Hx
386
Standard enthalpy of combustion of carbon (ΔHc ) is
-393.7 kJ/mol
387
Correct decreasing order of energy is
1 Cal > 1 Joule > 1 erg
388
Lesser the energy of a system
Greater is its stability
389
For the melting of ice H is
Positive
390
When an exothermic reaction is reversed it
Becomes an endothermic reaction
391
All types of energies of aprticels forming a system is called:
internal Energy
392
Spontenous reacton aer:
Uni-Directional
393
Spontaneous processes:
Move from non-equilibirum to equilibirum state
393
Spontaneous processes:
Move from non-equilibirum to equilibirum state
394
In order to predict whether reaction s spontaneous or non-spontaneous we should study:
Free energy chagne of the system
395
Which one of the following is incorrect to the first law of thermodynamics?
Energy of the universe tends to be either maxmum or minimum
396
We can keep the volume of a system constant, consisting o agas enclosng ia cylinder fitted with piston, by:
Fixing the postion of piston
397
Born Haber's Cylce is applicable to;
ionic compounds
398
The highest energy releasing step in Born Haber's cycle is;
Lattice Energy
399
The value of ΔV being very small, the term Δ(PV) can be neglected, for processes involving:
Solids and Liquids
400
The total heat contents of the system is called;
Enthalpy
401
The enthalpy of ionic compounds i calculated best with;
Born Haber Cycle
402
The enthapy change when one mole of compound is formed its elements at standard state is called:
Enthalpy of formation
403
Heat evolved or absorbed during reaction can be measured by using which formula:
q = mcΔT
404
Bomb calorimeter is used to determine the accurate enthalpy of:
Combustion
405
Energetically a chemica reation is independent of its path according to ___ law of thermochemistry
Second
406
For the reaction NH4Cl + aq ➡NH4Cl the enthalpy change is called:
Heat of solution
407
Enthalpy o neutralization is represented as:
ΔHn
408
Hes's law of constant summation is for each step mechanims:
Dependent
409
Which statement about internal energy is incorrect?
➡It is equal to sum of K.E. and P.E.❌
➡At constant volume ΔE=qv❌
➡It is expressed in Newton or Dynes✅
➡With the increase in internal energy the temperature of the system also increases❌
410
or the reaction CH3COOH ➡CH3COO- + H+ the change in enthalpy is called:
ENthalpy of ionization
411
It is common observation that asa result of chemical reaction, the energy is either evolved or absorbed in the fomr of:
Heat
412
During a chemical process which one is valid:
Total energy of the products is never equal to that of reactants
413
During an endothermic reacton:
Temperature of the surrounding will decrease and energy of the system will increase
414
The energy units in which heat chagnes are expressed in SI system are:
Joule
415
Thermochemsitry gives us information about:
➡Energy of heat contents of the compund
➡Energy involved n chemical bonding
➡Energy chagnes occurring n chemical equilibirum
416
Which is the Non-Spontaneous process?
Reaction of N2 and O2
417
To predict the spontaneity of reaction. It is necessary to study:
Free energy of the system
418
Ionic charge has ___ relationship with alttice energy.
Exponentially Direct
419
The potential energy of a system include:
➡All the types of bonds
➡Van der Waals forces present the particles
420
Which is the symbol of standard heat of formation?
ΔH
421
Which one of the following equations correctly defines the enthalpy change of formation of carbon monoxide?
C(s) + 1/2 O2 (g) ➡CO (g)
422
The value of the enthalpy change or the process represented by the equation Na (s) ➡Na+ (g) + e- is equal to;
The sum of the enthalpy change of atoizaton and the first ionization energy of sodium
423
Which one of the followng processes is endothermic?
The electrolysis of water
424
Which value would be requred to estimate the lattice nergy for the hypothetical ionic compound MgH2?
the standard enthalpy chage of formation of MgH2
425
Which equation represents the change corresponding to the enthalpy change of atomization of iodine?
1/2 I2 (s) ➡I (g)
426
From which of the following reactions can the bond energy of the C-F bonds be determined by usng only the standard enthalpy change of the reaction
C4 (g) ➡C(g) + 4F(g)
427
Which statement about the standard enthalpy change of ormation of carbon dioxide is correct?
It is equal to the standard enthalpy change of combustion of carbon
428
the following questons each represent a step in the Born-haber cycle for the enthalpy change of formation of sodium choride. Which changes have a negatvie ΔH value?
Cl (g) + e- ➡Cl- (g)
