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JAMB questions for "Chemistry :: Energy changes"
Q1
If a reaction is exothermic and there is a great disorder, it means that
A
there will be a large increase in free energy
B
there will be a large decrease in free energy
C
the reaction is static
D
the reaction is in a state of equilibrium
E
Q2

The graph above demonstrates the effect of

A

pressure on the rate of reaction

B

concentration on the rate of reaction

C

surface area on the rate of reaction

D

catalyst on the rate of reaction

E
Q3

In recharging a lead - acid accumulator, the reaction at the cathode can be represented as

A

Pb2+(aq) + SO2-4(aq) → PbSO4(s)

B

Pb2+(aq) + 2e-4(aq) → Pb(s)

C

Pb2+(aq) + 2H2O(l) → Pb2O(s) + 4H+ + 4e-

D

Pb(s) → Pb2+(aq) + 2e-

E
Q4

NH3(g) + HCl(g) → NH4Cl(s)

 

The entropy change in the system above is

A

positive

B

zero

C

negative

D

indeterminate

E
Q5

C2H4(g) + H2(g) → C2H6(g)  ΔH  = -137kJ mol-1

 

The reaction represented above is 

A

endothermic

B

exothermic

C

in equilibrium

D

spontaneous

E
Q6

In the diagram above, the respective activation energies for the catalysed and uncatalysed reactions in kJ are

A

50 and 45

B

45 and 50

C

40 and 45

D

30 and 35

E
Q7
A difference between chemical and physical change is that in a chemical change
A
oxygen is consumed
B
heat is supplied
C
a reversible process occurs
D
E
Q8
H2(g) + Br2(g) + 2HBr2(g)   The reaction above is carried out at 250C. If ΔH is -72kJ mol-1 and ΔS is -106 J mol-1 K-1, the reaction will 
A
not proceed spontaneously at the given temperature
B
proceed spontaneously at the given temperature
C
proceed in the reverse direction at the given temperature
D
proceed spontaneously at lower temperatures
E
Q9
Na2CO3(aq) + 2HCl(aq) → 2NaCl(aq) + H2O(l) + CO2(g)?   How many moles of sodium trioxocabonate (IV) are there in a 25cm3 solution which requires 10cm3 of 0.05 mol dm-3 hydrochloric acid solution to neutralize it
A
1.000 mole
B
0.100 mole
C
0.010 mole
D
0.001 mole
E
Q10
N2(g) + 3H2(g) ↔ 2NH3(g)  ΔH = -90kJ   In the equation above, the yield of ammonia can be decreased by
A
adding a catalyst
B
removing ammonia as it is formed
C
increasing the pressure
D
increasing the temperature
E
Q11
2H2 + O2 → 2H2O    ΔH = -571kJ   In the equation above, how much heat will be liberated if 12.0g of hydrogen is burnt in excess oxygen?
A
-1713 kJ
B
+1142 kJ
C
-571 kJ
D
-1142 kJ
E
Q12
2CO(g) + O2(g) →  2CO2(g)   Given that ΔH [CO] is -110.4kJ mol-1 and ΔH [CO2] is -393.0 kJ mol-1, the energy change for the reaction above is 
A
-282.6 kJ
B
+503.7 kJ
C
-503.7 kJ
D
+282.6 kJ
E
Q13
If an equilibrium reaction has ΔH > 0, the reaction will proceed favourably in the forward reaction at 
A
low temperature
B
high temperature
C
minimum emperature
D
any temperature
E
Q14
When cathode rays are deflected onto the electrode of an electrometer, the instrument becomes
A
bipolar
B
negatively charged
C
positivley charged 
D
neutral
E
Q15
P(g) + Q2(g) ↔ 3R(s) + S(g) ΔH is negative.   Which of the following will increase the yield of R?
A
Removing some S
B
using a large closed vessel
C
Adding a positive catalyst
D
Increasing the temperature
E
Q16
When ΔH is negative, a reaction is said to be  
A
endothermic
B
exothermic
C
reversible
D
ionic
E
Q17
C(s) + 2S(g) → CS2(g) ΔH = + 89 kJ mol-1   The chemical equation above implies that
A
89 kJ of energy is absorbed 
B
each of carbon and sulphur has 89 kJ of energy
C
both carbon and sulphur contribute 89 kJ of energy
D
89 kJ of energy is released
E
Q18
N2(g) + O2(g) ↔ 2NO(g) ; ΔH = +180.6 kJ mol-1.
A
increase the quantity of N2
B
increase the yield of NO
C
decrease the yield of NO
D
decrease the quantity of O2
E
Q19
a phenomenon where an element exists in different forms in the same physical state is kown as
A
isomerism
B
amophism
C
allotropy
D
isotopy
E
Q20
RS(aq) + HF(aq) → RF(s) + HS(aq) ΔH = -65.7kJ mol-1.   From the equation above, it can be deduced that 
A
the heat content of the reactant is lower than that of the product.
B
the heat content of the reactant is higher than that of the product.
C
the reaction is slow.
D
a large amount of heat is absorbed.
E
Q21
The entropy and enthalpy of a system are a measure of
A
degree of disorderliness and heat content respectively
B
heat content and degree of disorderliness respectively
C
heat content of a system only
D
degree of disorderliness only
E
Q22
In the diagram above, the activation energy for the backward reaction is
A
+5 kJ
B
+15 kJ
C
+25 kJ
D
+30 kJ
E
Q23
The addition of water to calcium oxide leads to
A
a physical change
B
a chemical change
C
the formation of a mixture
D
an endothermic change
E
Q24
2SO2(g) + O2 ↔ 2SO3(g). In the reaction above, the standard heats of formation of SO2(g) and SO3(g) are -297 kJ mol-1 and -396kJ mol-1 respectively. The heat chenge of the reaction is
A
-99 kJ mol-1
B
-198 kJ mol-1
C
+198 kJ mol-1
D
+683 kJ mol-1
E
Q25
˝N2(g) + ˝O(g) → NO(g) ΔHo = 89 kJ mol-1. If the entropy change for the reaction above at 25oC is 11.8kJ mol-1, calculate the change in free energy, ΔG, θ for the reaction at 25oC.
A
88.71 kJ
B
85.48 kJ
C
-204.00 kJ
D
-3427.40 kJ
E
Q26
If an equilibruim reaction has &#916;H < 0, the reaction will proceed favourably in the forward reaction at
A
low temperatures
B
high temperatures
C
all temperatures
D
all pressures
E
Q27
Which of the following processes leads to increase in entropy?
A
Mixing a sample of NaCl and sand
B
Condensation of water vapour
C
Boiling a sample of water
D
Cooling a saturated solution
E
Q28
The activation energy of the uncatalyzed reaction is
A
x
B
x + y
C
x - y
D
y
E
Q29
Which of the following ions will give a white precipitate with aqueous NaOH and soluble in excess of the base?
A
Ca2+
B
Mg2+
C
Zn2+
D
Cu2+
E
Q30
The &#916;H for the reaction represented by the energy profile above is
A
-100 kJ mol-1
B
+100 kJ mol-1
C
+50 kJ mol-1
D
-50 kJ mol-1
E
Q31
In the diagram above, the activation energy is represented by
A
y - x
B
x
C
x - z
D
y
E
Q32
A reaction takes place spontaneously if
A
&#916;G = O
B
&#916;S < O and &#916;H > O
C
&#916;H < T&#916;S
D
&#916;G > O
E
Q33
CaO(s) + H2O(I) &#8594; Ca(OH)2(s) &#916;H = -65kJ. The process represented by the above equation is known as
A
dissolution
B
slacking
C
liming
D
mortaring
E
Q34
1.1g of CaCl2 dissolved in 50cm3 of water caused a rise in temperature of 3.4oC. The heat of reaction, &#916;H for CaCl2 in kJ per mole is   [Ca = 40, Cl = 35.5, specific heat of water is 4.18 Jk-1]
A
-71.1
B
-4.18
C
+71.1
D
+111.0
E
Q35
NO(g) + CO(g) &#8596; ˝N2(g) + CO2(g) &#916;H = -89.3 kJ. What conditions would favour maximum conversion of nitrogen (II) oxide and carbon (II) oxide in the reaction above?
A
Low temperature and high pressure
B
High temperature and low pressure
C
High temperature and high pressure
D
Low temperature and low pressure
E
Q36
Which of the following gases will rekindle brightly glowing splint?
A
NO2
B
NO
C
N2O
D
Cl2
E
Q37
How many grams of bromine will be required to completely react with 10g of propyne   [C = 12, H = 1, Br = 80]
A
20 g
B
40 g
C
60 g
D
80 g
E
Q38
In the reaction   2Hl(g) &#8596; H2(g) + 12(g); &#916;H = 10kJ   the concentration of iodine in the equilibruim mixture can be increased by
A
raising the pressure
B
raising the temperature
C
adding a catalyst
D
lowering the pressure
E
Q39
The combustion of ethene, C2H2, is given by the equation C2H4 + 2H2O;&#916;H = -1428kJ. If the molar heats of formation of water and carbon (VI) oxide are -286kJ and -396kJ respectively, calculate the molar heat of formation of ethene in kJ
A
-2792
B
+2792
C
-64
D
+64
E
Q40
CO(g) + H2O(g) &#8596; CO2(g) + H2(g) &#916;H = -41000J.   Which of the following factors favour the formation in the above reaction? (I) high pressure (II) low pressure (III) high temperature (IV) use of excess steam
A
I, III and IV
B
III only
C
II, III and I
D
IV only 
E
Q41
What volume of a 0.1 MH3PO4 will be required to neutralize 45.0 cm3 of a 0.2M NaOH?
A
10.0 cm3
B
20.0 cm3
C
27.0 cm3
D
30.0 cm3
E
Q42
Which of the following statements is TRUE?
A
The dissolution of NaOH(s) in water is endothermic
B
The heat of solution of NaOH(s) is positive
C
The NaOH(s) gains heat from the surroundings
D
The heat of solution of of NaOH(s) is negative 
E
Q43
Which property of a reversible reaction is affected by a catalyst?
A
Heat content (enthalphy)
B
Energy of activation
C
Free energy change
D
Equilibruim position
E
Q44
If the molar mass of X is 36 g, the number of mole of X dissolved at 343 K is
A
0.2 moles
B
0.7 moles
C
1.5 moles
D
2.0 moles
E
3.0 moles
Q45
The energy change (&#916;H) for the reaction CO(g)˝O2 &#8594; CO2(g) is
A
-503.7 kJ
B
+503.7 kJ
C
-282.9 kJ
D
+282.9 kJ
E
+393.3 kJ
Q46
The diagram beside (Fig. 3) shows the energy profile for the reaction A + B = C + D. From this diagram, it is clear that the reaction is
A
spontaneous
B
isothermal
C
adiabatic
D
exothermic
E
endothermic
Q47
In the reaction M+ N &#8596; P; &#916;H = + Q kJ. Which of the following would increase the concentration of the product?
A
Decrease the concentration of N.
B
Increase the concentration of P.
C
Adding a suitable catalyst.
D
Decreasing the temperature.
E
Increasing the temperature.
Q48
In the above experiment (Fig 2.) , a current was passed for 10 minutes and 0.63g of copper was to be deposited on the cathode of CuSO4 cells. The weight of silver deposited on the cathode of AgNO3 cell during the same period would be (Cu = 63, Ag = 108)
A
0.54g
B
1.08g
C
1.62g
D
2.16g
E
3.24g
Q49
In the reactions   (I)   H2(g) + ˝O2 &#8594; H2O (l); &#916;H = -286kJ   (II)  C(s) + O2(g) CO2 (g); &#916;H = -406kJ the equations imply that
A
more heat is absorbed in (I)
B
more heat is absorbed (II)
C
less heat is absorbed in (I)
D
reaction (II) proceeds faster than (I)
E
reaction (I) proceeds faster than (II)
Q50
What volume of 0.5 MH2SO4 will exactly neutralize 20cm3 of 0.1 M NaOH solution?
A
2.0 cm3
B
5.0 cm3
C
6.8 cm3
D
8.3 cm3
E
10.4 cm3
Q51
In the manufacturing of ammonia by the reaction N2(g)  + 3H2(g) &#8596; 2NH3 (g) &#916;&#919; = -92.37kJ, the amount of ammonia formed at equilibruim will increase if
A
the pressure decreases
B
the temperature increases
C
the temperature decreases
D
a catalyst is used
E
the physical state of the reactants are changed
Q52
Which of the following processes does NOT lead to a chemical change?
A
Stirring iron in sulphur (VI) acid
B
Stirring sodium carbonate in water
C
Stirring glucose in concentrated sulphur (VI) acid
D
Mixing sulphur (VI) acid with potassium carbonate
E
Titrating an acid against a base
Q53
When sodium nitrate dissolves in water, &#916;H is positive. This means that
A
the reaction is catalyzed
B
the reaction is complete
C
the reaction is exothermic
D
the reaction is endothermic
E
sodium nitrate is highly soluble in water
Q54
20 cm3 of 1M H2SO4 is mixed with 20 cm3 of 1 M naOH. The resulting solution is
A
acidic with a molarity of 0.50 M H2SO4
B
acidic with a molarity of 0.25 M H2SO4
C
neutral
D
alkaline with a molarity of 0.25 M NaOH
E
alkaline with a molarity of 0.50 M NaOH
Q55
An endothermic reaction is one during which heat is.... and can be represented by the symbol.... Which of the following combinations can be used accurately to complete the above defination?
A
liberated, -&#916;H
B
liberated, +&#916;H
C
absorbed, -&#916;H
D
absorbed, +&#916;H
E
absorbed, +&#916;G
Q56
The following reactions are stages in important industrial processes:   I.    N2(g) + 3H2(g) &#8596; 2NH3(g)   &#916;H is negative II.   2SO2(g) + O2(g)                 &#916;H is negative III.  N2(g) + O2 &#8596; 2SO3(g)         &#916;H is positive   Which of the above forward reactions is favoured by (I) a decrease in the concentration of the pressure and (II) an increase in temperature?
A
I
B
II
C
III
D
I and II
E
I and III
Q57
The reaction between hydrogen and iodine my be represented by the equation   H2(g) + I2(g) &#8596; 2Hl(g)  and is exothermic. Therefore
A
an increase in temperature favours the forward reaction
B
an increase in pressure favours the backward reaction
C
both pressure and temperature must be increased to favour the forward reaction
D
a decrease in temperature  favour the forward reaction
E
a decrease in pressure  and increase in temperature will favour the forward reaction
Q58
When sodium chloride and metallic sodium are each dissolved in water
A
both processes are exothermic
B
both processes are endothermic
C
the dissolution of metalic sodium is endothermic
D
the dissolution of metalic sodium is exothermic
E
the dissolution of sodium chloride is explosive
Q59
When Sodium Chloride and metallic sodium are each dissolved in water
A
both processes are exothermic.
B
both processes are endothermic.
C
the dissolution of metallic sodium is endothermic.
D
the dissolution of metallic sodium is exothermic.
E
the dissolution of metallic sodium is explosive.
Q60
When heat is absorbed during a chemical reaction, the reaction is said to be
A
thermodynamic
B
exothermic
C
isothermal
D
endothermic
E
thermostatic