Download holiday home work - chemistry- xii-sc

HOLIDAY HOME WORK - CHEMISTRY- XII-SC
In which equation is the metal reduced?
[Cr2O7]2–+ 2[OH]– → 2[CrO4]2– + H2O
2[MnO4]– + 5[C2O4]2– + 16H+ → 2Mn2+ + 10CO2 + 8H2O
CuCO3 + 2HCl → CuCl2 + CO2 + H2O
Mg + 2HCl → MgCl2 + H2
Which statement is correct about the Daniell cell?
The spontaneous cell reaction involves the reduction of Cu2+ to Cu.
The spontaneous cell reaction involves the oxidation of Cu by Zn2+.
The Daniell cell is an example of an electrolytic cell.
The spontaneous cell reaction involves the reduction of Zn2+ to Zn.
For the reaction:
2Ag+ + Zn → 2Ag + Zn2+
Eocell = 1.56 V. What is the corresponding value of ΔGo?
–301 kJ mol–1
301 kJ mol–1
–301 J mol–1
301 J mol–1
For the reaction:
2H+ + Zn → H2 + Zn2+
ΔGo = –147 kJ mol–1. What is the corresponding value of Eocell?
1.52 V
–1.52 V
–0.76 V
0.76 V
For the reaction:
2H+ + Mg → H2 + Mg2+
ΔGo = –457 kJ mol–1. What is the value of Eo(Mg2+/Mg)?
–2.37 V
+4.74 V
–4.74 V
+2.37 V
If a silver strip were immersed in an aqueous solution
containing Cu2+ ions, what would you expect to happen?
No reaction would occur.
Copper would be deposited on the silver strip.
Cu2+ ions would be reduced.
Ag would be oxidized.
Eo(Ag+/Ag) = +0.80 V. What is the value of E (at 298 K) when
the concentration of the Ag+ ions is 0.0150 mol dm–3?
+0.75 V
+0.69 V
+0.91 V
+0.85 V
For which of the following half-cells is E independent of the pH
of the solution?
Co2+ + 2e–
Co
[Cr2O7]2– + 14H+ + 6e
[NO3]– + H2O + 2e–
H2O2 + 2H+ + 2e–
2Cr3+ + 7H2O
[NO2]– + 2[OH]–
2H2O
Which manufacturing process depends upon electrolysis?
Contact process.
Haber process.
Czochralski process.
Downs process.
An electrochemical cell consists of two copper electrodes
dipping into aqueous CuSO4 solution; the electrodes are
connected to a battery. Which statement about the electrolysis
process in this cell isincorrect?
Cu2+ ions are produced at the anode.
Copper in transferred from anode to cathode.
Reduction occurs at the anode.
Copper is deposited on the cathode.
How much Cu metal is produced at the cathode during the
electrolysis of aqueous CuSO4 solution if a current of 0.10 A
passes through the solution for 20 min?
6.2 × 10–4 moles
2.0 × 10–5 moles
1.2 × 10–3 moles
1.0 × 10–5 moles
Which statement is incorrect about an electrolytic cell?
Reduction occurs at the cathode.
The electrodes may be inert (e.g. graphite) or may be involved in the
cell reaction.
The cell includes a battery.
The cell reaction is spontaneous.
A pH meter is an example of:
an ion-selective electrode.
an electrolytic cell.
a fuel cell.
a reference electrode.
Values of Eo for the Ce4+/Ce3+ and Fe2+/Fe half-cells are +1.72
and –0.44 V, respectively. From these data you can conclude
that:
Ce3+ is a better oxidizing agent than Fe2+.
Ce3+ will oxidize Fe.
Ce4+ is a better oxidizing agent than Fe2+.
Ce4+ will oxidize Fe2+.
Eo(Cu2+/Cu) = +0.34 V. What is the value of E (at 298 K) for an
aqueous solution in which [Cu2+] = 0.02 mol dm–3.
0.29 V
0.32 V
0.39 V
0.36 V
What is the value of ΔGo(298 K) for the reaction between Cl2 and
I– ions if the Eo values for the Cl2/Cl– and I2/I– half-cells are
+1.36 and +0.54 V, respectively? Give your answer per mole of
Cl2.
–79 J mol–1
–158 kJ mol–1
–158 J mol–1
–79 kJ mol–1
In acidic solution, H2O2 oxidizes Fe2+ to Fe3+. What is the value
of ΔGo(298 K) for the reaction given the following data?
Fe3+(aq) + e–
Fe2+(aq)
H2O2(aq) + 2H+(aq) + 2e–
–106 J per mole of Fe3+
–212 J per mole of H2O2
–212 kJ per mole of H2O2
–212 kJ per mole of Fe3+
Which of the following
statements is incorrect?
An external power supply
is needed in an electrolytic
cell.
In a galvanic cell, the
passage of a current
through an electrolyte
drives a redox reaction.
In a Daniell cell, a
difference in electrical
potentials of the two halfcells results in a flow of
electrons between the
half-cells.
Copper can be purified
using an electrolytic cell.
Eo = 0.77 V
2H2O(l)
Eo = 1.87 V
1) Consider the reaction: A → 2C
The average rate of appearance of C is given by Δ[C]/Δt.
Comparing the rate of appearance of C and the rate of
disappearance of A, we get [C]/ t = _____ ([A]/t)
A) +2 B) -1 C) +1
D) +1/2 E) -1/2
A flask is charged with 0.124 mol of A and allowed to react to form B
according to the reaction A(g) →B(g). The following data are
obtained for [A] as the reaction proceeds:
Time(s) 1 10 20 30 40
Moles of A 0.124 0.110 0.088 0.073 0.054
2) The average rate of disappearance of A between 20 s and 40
s is __________ mol/s.
A) 8.5 × 10-4 B) 1.7 × 10-3 C) 590
D) 7.1 × 10-3 E) 1.4 × 10-3
4) How many moles of B are present at 10 s?
A) 0.011 B) 0.220 C) 0.110
D) 0.014 E) 1.4 × 10-3
The peroxydisulfate ion 22 8 (S O ) reacts with the iodide ion in
aqueous solution via the reaction:
2- - -
O ) (aq) + 3I 2SO (aq) + I3 (aq)
An aqueous solution containing 0.050 M of 22 8 4 (S
28
S O ion and
0.072 M of I- is prepared, and the progress of the reaction
followed by measuring [I-]. The data obtained is given below.
Time(s) 0 400 800 1200 1600
[I-] (M) 0.072 0.057 0.046 0.037 0.029
5) The average rate of disappearance of I in the initial 400 s is
__________ M/s.
A) 6.00 B) 3.8 × 10-5 C) 1.4 × 10-4
D) 2.7 × 104 E) 3.2 × 10-4
6) The concentration of S2O82- remaining at 800 s is ____ M.
A) 0.046 B) 0.076 C) 4.00 × 10-3
D) 0.015 E) 0.041
7) At elevated temperatures, methylisonitrile (CH3NC)
isomerizes to acetonitrile (CH3CN):
CH3NC (g) → CH3CN (g)
At the start of the experiment, there are 0.200 mol of reactant
(CH3NC) and 0 mol of product (CH3CN) in the reaction
vessel. After 25 min of reaction, 0.108 mol of reactant
(CH3NC) remain. The average rate of decomposition of
methyl isonitrile, CH3NC, in this 25 min period is __ mol/min.
A) 3.7 × 10-3 B) 0.092 C) 2.3
D) 4.3 × 10-3 E) 0.54
8) If the rate law for the reaction 2A + 3B → products is
first order in A and second order in B, then the rate law is ____.
A) rate = k[A][B] B) rate = 2 3 k[A] [B]
C) rate = 2 k[A][B] D) rate = 2 k[A] [B]
E) rate = k[A]2[B]2
9) The overall order of a reaction is 2. The units of the rate
constant for the reaction are __________.
A) M/s B) -1 -1
M s C) 1/s
D) 1/M E) 2 s/M
10) The kinetics of the reaction below were studied and it was
determined that the reaction rate increased by a factor of 9
when the concentration of B was tripled. The reaction is
__________ order in B.
A+B→P
A) zero B) first C) second
D) third E) one-half
11) A reaction was found to be third order in A. Increasing the
concentration of A by a factor of 3 will cause the reaction rate
to __________.
A) remain constant B) increase by a factor of 27
C) increase by a factor of 9 D) triple
E) decrease by a factor of the cube root of 3
12) A reaction was found to be zero order in A. Increasing the
concentration of A by a factor of 3 will cause the reaction rate
to __________.
A) remain constant B) increase by a factor of 27
C) increase by a factor of 9 D) triple
E) decrease by a factor of the cube root of 3
The data in the table below were obtained for the reaction:
A+B→P
Experiment
Number
[A] (M) [B] (M) Initial Rate
(M/s)
1 0.273 0.763 2.83
2 0.273 1.526 2.83
3 0.819 0.763 25.47
13) The order of the reaction in A is __________.
A) 1 B) 2 C) 3
D) 4 E) 0
14) The order of the reaction in B is __________.
A) 1 B) 2 C) 3
D) 4 E) 0
15) The overall order of the reaction is __________.
A) 1 B) 2 C) 3
D) 4 E) 0
16) The magnitude of the rate constant is __________.
A) 38.0 B) 0.278 C) 13.2 D) 42.0 E) 2.21
18) The rate constant for a particular second-order reaction is
0.47 -1 -1
M s . If the initial concentration of reactant is 0.25
mol/L, it takes __________ s for the concentration to decrease
to 0.13 mol/L.
A) 7.9 B) 1.4 C) 3.7
D) 1.7 E) 0.13
19) The initial concentration of reactant in a first-order
reaction is 0.27 M. The rate constant for the reaction is -1
0.75 s
What is the concentration (mol/L) of reactant after 1.5 s?
A) 3.8 B) 1.7 C) 8.8 × -2
10
D) 2.0 × -2
10 E) 0.135
20) The half-life of a first-order reaction is 13 min. If the initial
concentration of reactant is 0.085 M, it takes ________min for
it to decrease to 0.055 M.
A) 8.2 B) 11 C) 3.6
D) 0.048 E) 8.4
21) The reaction below is first order in 2 2 [H O ] :
2 2 2 2 2H O (l) 2H O (l) + O (g)
A solution originally at 0.600 M 2 2
H O is found to be 0.075 M
after 54 min. The half-life for this reaction is __________ min.
A) 6.8 B) 18 C) 14
D) 28 E) 54
22) Of the following, all are valid units for a reaction rate
except __________.
A) mol/L B) M/s C) mol/hr
D) g/s E) mol/L-hr
24) The rate law of a reaction is rate = k[D][X]. The units of
the rate constant are __________.
A) -1 -1 mol L s B) -1 -1 L mol s
C) mol2 L -2s-1 D) -1-2mol L s
E) 2 -2 -1 L mol s
25) The half-life of a first-order reaction __________.
A) is the time necessary for the reactant concentration to drop
to half its original value
B) is constant
C) can be calculated from the reaction rate constant
D) does not depend on the initial reactant concentration
E) All of the above are correct.
27) The rate constant for this reaction is __________ -1s .
A) 0.013 B) 0.030 C) 0.14
D) 3.0 E) 3.1 × -310
28) The half-life of this reaction is __________ s.
A) 0.97 B) 7.1 C) 4.9
D) 3.0 E) 0.14
29) At elevated temperatures, methylisonitrile (CH3NC)
isomerizes to acetonitrile (CH3CN):
CH3NC (g) → CH33CN (g)
The reaction is first order in methylisonitrile. The attached
graph shows data for the reaction obtained at 198.9°C.
The rate constant for the reaction is __________ s-1.
A) -1.9 × 104 B) +1.9 × 104
C) -5.2 × 10-5 D) +5.2 × 10-5
E) +6.2
30) As the temperature of a reaction is increased, the rate of
the reaction increases because the __________.
A) reactant molecules collide less frequently
B) reactant molecules collide with greater energy per collision
C) activation energy is lowered
D) reactant molecules collide less frequently and with greater
energy per collision
E) reactant molecules collide more frequently with less energy
per collisionk2
31) In the energy profile of a reaction, the species that exists at
the maximum on the curve is called the __________.
A) product B) activated complex
C) activation energy D) enthalpy of reaction
E) atomic state
32) In the Arrhenius equation, -Ea/RT k = Ae
__________ is the frequency factor.
A) k B) A C) e D) a E E) R
33) In general, as temperature goes up, reaction rate _______.
A) goes up if the reaction is exothermic
B) goes up if the reaction is endothermic
C) goes up regardless of whether the reaction is exothermic or
endothermic
D) stays the same regardless of whether the reaction is
exothermic or endothermic
E) stays the same if the reaction is first order
34) At elevated temperatures, methylisonitrile (CH3NC)
isomerizes to acetonitrile (CH3CN):
CH3NC (g) → CH3CN (g)
The dependence of the rate constant on temperature is studied
and the graph below is prepared from the results.
The energy of activation of this reaction is __________ kJ/mol.
A) 160 B) 1.6 × 105 C) 4.4 × 10-7
D) 4.4 × 10-4 E) 1.9 × 104
35) The mechanism for formation of the product X is:
A + B → C + D (slow)
B + D → X (fast)
The intermediate reactant in the reaction is __________.
A) A B) B C) C
D) D E) X
36) For the elementary reaction 3 2 2
NO + CO NO + CO
the molecularity of the reaction is __________, and the rate law
is rate = __________.
A) 3 2, k[NO ][CO] B) 3 2 2 4, k[NO ][CO][NO ][CO ]
C) 2 2 2, k[NO ][CO ] D) 3 2 2 2, k[NO ][CO]/[NO ][CO ]
E) 2 2 3 4, k[NO ][CO ]/[NO ][CO]
37) A possible mechanism for the overall reaction
2 Br (g) + 2NO (g) 2NOBr (g)
is k1
NO (g) + Br2 (g) NO Br2 (g) (fast)
NO Br2 (g) + NO (g) 2NOBr (slow)
The rate law for formation of NOBr based on this mechanism is
rate = ________.
A) 1/2
1 k [NO] B) 1/21 2 k [Br ]
C) -1 2
2 1 2 (k k /k )[NO] [Br ]
D) -1 2 21 (k /k ) [NO] E) -1 22 1 2 (k k /k )[NO][Br ]
38) Of the following, __________ will lower the activation
energy for a reaction.
A) increasing the concentrations of reactants
B) raising the temperature of the reaction
C) adding a catalyst for the reaction
D) removing products as the reaction proceeds
E) increasing the pressure
39) A catalyst can increase the rate of a reaction __________.
A) by changing the value of the frequency factor (A)
B) by lowering the overall activation energy (Ea ) of the
reaction
C) by lowering the activation energy of the reverse reaction
D) by providing an alternative pathway with a lower activation
energy
E) All of these are ways that a catalyst might act to increase the
rate of reaction.
40) The combustion of ethylene proceeds
by the reaction 2 4 2 2 2 C H (g) + 3O (g) 2CO (g) + 2H O (g)
When the rate of disappearance of 2
O is 0.28 -1
M s , the rate of
appearance of 2
CO is __________ -1
Ms.
A) 0.19 B) 0.093 C) 0.84
D) 0.42 E) 0.56