2010 Ionic Eqm MCQ PDF
2010 Ionic Eqm MCQ PDF
2010 Ionic Eqm MCQ PDF
Which
statement
about
the
titration
is
correct?
A Both
an
acidic
and
basic
buffer
can
be
formed
at
different
points
during
this
titration.
B Both
phenolphthalein
and
methyl
orange
can
be
used
as
an
indicator
for
this
titration.
C Ethanoic
acid
is
used
in
this
titration
and
it
has
a
pKa
value
of
less
than
4.
D Benzoic
acid
is
used
in
this
titration
and
it
has
a
similar
concentration
as
NaOH.
CJC
Prelim
2010
6 The
table
below
shows
the
values
of
the
ionic
product
of
water,
Kw,
at
two
different
temperatures.
Temperature
/
Kw
/
mol2
dm 6
−
o
C
25
1.00
×
10 14
−
62
1.00
×
10 13
−
Which
of
the
following
statements
is
correct
for
pure
water?
A The
ionic
dissociation
of
water
is
an
exothermic
process.
B At
62
oC,
pH
=
14
−
pOH.
C At
62
oC,
pH
<
pOH.
D At
62
oC,
pH
<
7.
HCI
Prelim
2010
7 Which
of
the
following
graphs
correctly
represents
the
variation
of
pH
against
the
volume
of
nitric
acid
added
when
20.0
cm3
of
a
0.2
mol
dm-‐3
sodium
carbonate
solution
is
titrated
against
0.2
mol
dm-‐3
nitric
acid
using
phenolphthalein
and
methyl
orange
indicators?
IJC
Prelim
2010
8 The
pH
of
a
solution
mixture
containing
equal
amounts
of
aqueous
ammonia
and
ammonium
chloride
is
9.26.
Which
of
the
following
happens
when
2.0
cm3
of
0.10
mol
dm-‐3
nitric
acid
is
added
to
the
mixture?
A The
pH
of
the
resulting
solution
increases.
B The
number
of
moles
of
NH4+
ions
in
the
resulting
solution
increases.
C The
number
of
moles
of
NH3
molecules
in
the
resulting
solution
remains
unchanged.
D The
ratio
of
moles
of
NH4+
ions
to
NH3
molecules
in
the
resulting
solution
decreases.
IJC
Prelim
2010
3 −3
3
9 When
5.00
cm
of
a
0.100
mol
dm base
is
titrated
against
0.100
mol
dm
of
−
Which
of
the
following
correctly
identifies
the
base
used
and
the
point
on
the
curve
at
which
pH
=
pKa?
Based
used
Point
where
pH
=
pKa
A
KOH(aq)
M
B
Ba(OH)2(aq)
N
C
KOH(aq)
P
D
Ba(OH)2(aq)
P
JJC
Prelim
2010
10 Equal
volumes
of
solutions
of
ethanoic
acid
and
hydrochloric
acid,
of
equal
concentration,
are
compared.
In
which
of
the
following
cases
does
the
ethanoic
acid
give
the
higher
value?
A pH
of
solution
B Conductivity
of
solution
C Rate
of
reaction
with
magnesium
D Volume
of
sodium
hydroxide
solution
neutralized
MI
Prelim
2010
11 The
position
of
equilibrium
lies
to
the
right
in
each
of
these
reactions.
N2H5+
+
NH3 NH4+
+
N2H4
NH3
+
HBr NH4+
+
Br–
N2H4
+
HBr N2H5+
+
Br–
Based
on
this
information,
what
is
the
order
of
acid
strength?
A
HBr
>
N2H5+
>
NH4+
B
N2H5+
>
N2H4
>
NH4+
C
NH3
>
N2H4
>
Br–
D
N2H5+
>
HBr
>
NH4+
MI
Prelim
2010
12 The
following
reaction
takes
place
using
liquid
ammonia
as
a
solvent.
NaNH2
+
NH4Cl
→
NaCl
+
2NH3
Which
statement
best
explains
why
this
reaction
should
be
classified
as
a
Bronsted-‐
Lowry
acid-‐base
reaction?
A NH3
is
basic.
B NaCl
is
neutral.
C NH4Cl
is
a
salt.
D NH2
is
a
proton
acceptor.
−
MJC
Prelim
2010
13 The
graph
shows
the
change
in
pH
when
an
aqueous
base
is
gradually
added
to
25
cm3
of
an
acid.
Which
pair
of
solutions
will
give
these
results?
A 0.10
mol
dm-‐3
HCl
and
0.05
mol
dm-‐3
NH3
B 0.10
mol
dm-‐3
HCl
and
0.10
mol
dm-‐3
NaOH
C 0.05
mol
dm-‐3
H2SO4
and
0.10
mol
dm-‐3
NH3
D 0.10
mol
dm-‐3
CH3COOH
and
0.10
mol
dm-‐3
NaOH
MJC
Prelim
2010
14 Nitrogen
is
discharged
from
wastewater
treatment
facilities
into
rivers
and
streams,
usually
as
NH3
and
NH4+.
One
strategy
for
removing
the
nitrogen
is
to
raise
the
pH
and
strip
the
NH3
from
the
water
to
be
discharged
by
bubbling
air
through
the
water.
The
fraction
of
the
total
nitrogen
present
in
the
water
to
be
discharged
is
defined
as:
[NH3 ]
[NH3 ]+[NH4+ ]
Given
that
the
base
dissociation
constant,
Kb
of
NH3
is
1.76
x
10 5
mol
dm 3,
what
is
− −
the
fraction
of
the
total
nitrogen
in
the
water
to
be
discharged
at
pH
7.00?
A
0.994
B
0.500
C
-‐5.65
x
10 3
−
D
1.76
x
10 3
−
NYJC
Prelim
2010
15 Solution
W
is
prepared
by
mixing
0.5
mol
of
benzoic
acid,
C6H5CO2H
and
0.2
mol
of
sodium
hydroxide,
NaOH.
Which
diagram
shows
how
the
pH
varies
when
an
aqueous
alkali
is
added
to
solution
W?
NYJC
Prelim
2010
16 25
cm3
of
0.10
mol
dm–3
of
aqueous
ammonia
was
added
to
10
cm3
of
0.20
mol
dm–
3
hydrochloric
acid.
What
is
the
pH
of
the
resulting
solution?
The
pKb
value
for
aqueous
ammonia
is
4.75.
A
3.30
B
5.35
C
8.65
D
10.70
RJC
Prelim
2010
17 Which
of
the
following
conjugate
acid-‐base
pairs
can
be
used
to
prepare
a
buffer
of
approximately
pH
6
that
has
maximum
buffer
capacity?
A NH4+
/
NH3
Kb
of
NH3
=
1.78
x
10 5
mol
dm 3
− −
B H2CO3
/
HCO3
−
Kb
of
HCO3
=
2.38
x
10 8
mol
dm 3
− − −
C H3PO4
/
H2PO4
−
Kb
of
H2PO4
=
1.33
x
10 12
mol
dm 3
− − −
D CH3COOH
/
CH3COO
−
Kb
of
CH3COO
=
5.71
x
10 12
mol
dm 3
− − −
RJC
Prelim
2010
3 3
18 In
an
acid-‐base
titration,
a
0.20
mol
dm
solution
of
a
base
is
added
to
25
cm
of
a
−
The
pH
value
of
the
solution
is
plotted
against
the
volume
of
base
added,
V,
as
shown
in
the
diagram.
This
diagram
could
represent
a
titration
between
A CH3COOH(aq)
and
NH3(aq).
B HCl(aq)
and
Ba(OH)2(aq).
C H2SO4(aq)
and
NaOH(aq).
D HNO3(aq)
and
NH3(aq).
RVHS
Prelim
2010
19 The
graph
below
shows
the
pH
change
when
25.0
cm3
of
0.100
mol
dm-‐3
aqueous
HCl
was
titrated
against
0.100
mol
dm-‐3
methylamine.
The
Kb
of
methylamine
is
4.37
x
10-‐4
mol
dm-‐3.
What
is
the
pH
of
the
solution
when
12.5
cm3
of
methylamine
was
added?
A
1.48
C
2.90
D
3.36
D
10.6
SAJC
Prelim
2010
20 What
is
the
pH
of
a
solution
formed
by
mixing
0.45
g
of
lactic
acid
and
0.84
g
of
sodium
lactate
in
a
500
cm3
beaker?
(Given
Ka
of
lactic
acid
=
1.34
x
10-‐4
mol
dm-‐3,
Mr
of
lactic
acid
=
90,
Mr
of
sodium
lactate
=
112)
A
3.60
C
3.87
B
3.70
D
4.05
SRJC
Prelim
2010
21 The
pKb
value
for
aqueous
ammonia
at
25
°C
is
4.80.
What
is
the
pH
of
a
solution
containing
100
cm3
of
0.440
mol
dm-‐3
aqueous
ammonia
and
100
cm3
of
0.240
mol
dm-‐3
of
hydrochloric
acid?
A
4.72
C
9.12
B
4.88
D
9.28
TJC
Prelim
2010
22 The
equilibrium
constant
for
the
hydrolysis
of
the
cobalt(II)
cation,
Kh,
is
defined
as
Co(H2O)6
2+(aq)
+
H2O(l)
⇌
[Co(H2O)5(OH)]+(aq)
+
H3O+(aq)
[Co(H2O)5 (OH)+ ] [H3O+ ]
Kh =
[Co(H2O)6 2+ ]
Given
that
Kh
=
5.0
Ï
10
mol
dm ,
what
is
the
pH
of
a
0.200
mol
dm-‐3
CoBr2
-‐10 -‐3
solution?
A
4.3
C
6.5
B
5.0
D
10.0
VJC
Prelim
2010
− 2− 2− −
23 H2PO4
+
HBO3
HPO4
+
H2BO3
The
equilibrium
constant
for
the
above
reaction
represented
by
the
equation
is
greater
than
1.0.
Which
of
the
following
gives
the
correct
relative
strength
of
the
acids
and
bases
in
the
reaction?
A H2PO4−
>
H2BO3−
and
HBO32−
>
HPO42−
B H2BO3−
>
H2PO4−
and
HBO32−
>
HPO42−
C H2PO4−
>
H2BO3−
and
HPO42−
>
HBO32−
D H2BO3−
>
H2PO4−
and
HPO42−
>
HBO32−
YJC
Prelim
2010
24 The
pH
range
and
color
changes
for
two
acid-‐base
indicators
are
given
below.
Indicator
pH
range
X
violet
3.0
–
5.0
red
Y
yellow
5.6
–
7.6
blue
A
solution
in
which
X
is
red
and
Y
is
yellow
is
A 0.1
mol
dm-‐3
HCl
B 0.1
mol
dm-‐3
CH3COOH
(Ka
=
1.8
x
10-‐5
mol
dm-‐3)
C 0.1
mol
dm-‐3
HX
(Ka
=
2.5
x
10-‐10
mol
dm-‐3)
D 0.1
mol
dm-‐3
NH3
(Kb
=
1.8
x
10-‐5
mol
dm-‐3)
YJC
Prelim
2010
The
responses
A
to
D
should
be
selected
on
the
basis
of
A
B
C
D
1,
2
and
3
1
and
2
only
2
and
3
only
1 only
is
are
correct
are
correct
are
correct
correct
25 H2O
auto-‐ionises
as
shown
by
the
equation
below.
2H2O
H3O+
+
OH-‐
The
ionic
product
of
water
is
given
by
the
expression
Kw
=
[H3O+][OH-‐]
which
increases
with
increasing
temperature.
What
conclusions
can
be
drawn
about
this
reaction?
1. The
pH
of
hot
water
is
smaller
than
that
of
cold
water.
2. The
electrical
conductivity
of
hot
water
is
greater
than
that
of
cold
water.
3. The
dissociation
of
water
is
exothermic.
YJC
Prelim
2010
26 The
table
below
gives
the
acid
dissociation
constants,
Ka,
of
three
acids,
at
298
K.
Acids
Formula
Ka /
mol
dm-‐3
-‐5
Ethanoic
acid
CH3COOH
1.8
x
10
-‐3
Chloroethanoic
acid
CH2ClCOOH
1.3
x
10
-‐10
Phenol
C6H5OH
1.3
x
10
Which
of
the
following
statement(s)
is/are
correct?
1. An
acidic
buffer
of
pH
=
2.89
is
formed
by
mixing
equal
volumes
of
same
concentration
of
CH2ClCOOH
and
CH2ClCOONa.
2. An
acidic
buffer
of
pH
=
4.74
is
formed
by
mixing
25
cm3
of
0.100
moldm-‐3
of
CH3COOH
with
12.5
c
m3
of
0.100
mol
dm-‐3
of
Ba(OH)2.
3. pH
of
0.100
mol
dm-‐3 phenol
is
1.
ACJC
Prelim
2010
27 Concentrated
sulfuric
acid
behaves
as
a
strong
acid
when
it
reacts
with
water.
H2SO4(l)
+
aq
→
H+(aq)
+
HSO4–(aq)
The
HSO4–
ion
formed
behaves
as
a
weak
acid.
SO4–(aq)
H+(aq)
+
SO42–(aq)
Which
statements
are
true
for
1.0
mol
dm–3
sulfuric
acid?
1. [H+(aq)]
is
high
2. [SO42–(aq)]
is
high
3. [HSO4–(aq)]
=
[SO42–(aq)]
AJC
Prelim
2010
28 Which
of
the
following
aqueous
solution
do
not
considerably
change
in
pH
when
relatively
small
volumes
of
strong
acid
or
strong
alkali
are
added?
1. A
mixture
of
HF
and
NaF
2. A
mixture
of
HCN
and
NaCN
3. A
mixture
of
HO2C–CH2–NH3+
and
–O2C–CH2–NH3+
AJC
Prelim
2010
29 The
titration
curve
of
the
protonated
form
of
an
amino
acid
is
as
shown.
The
two
stages
of
titration
are
associated
with
two
different
dissociation
constants,
K1
and
K2.
Which
statements
are
always
correct
for
any
amino
acid?
1. The
form
H3N+CHRCO2
is
the
most
common
species
present
at
pH
7.
−
2. Equal
concentrations
of
H3N+CHRCO2H
and
H3N+CHRCO2
are
present
at
pH
=
pK1.
−
3. There
is
no
net
charge
on
the
amino
acid
at
the
point
when
the
slope
of
the
curve
is
at
a
maximum
at
its
centre.
HCI
Prelim
2010
30 Some
data
on
two
acid-‐base
indicators
are
shown
below.
Indicator
Approximate
pH
range
Colour
change
Acid
Alkali
bromocresol
green
3.8
–
5.5
yellow
blue
phenol
red
6.8
–
8.5
yellow
red
Which
one
of
the
following
conclusions
can
be
drawn
about
a
solution
in
which
bromocresol
green
is
blue
and
phenol
red
is
yellow?
1. It
is
weakly
acidic.
2. It
can
be
a
solution
of
ammonium
sulfate.
3. It
can
be
a
solution
of
sodium
ethanoate.
PJC
Prelim
2010
31 The
pKa
values
of
the
following
compounds
are
given
below.
Compound
pKa
H2CO3
6.4
CF3COOH
0.2
CH3CH2OH
16.0
10.0
OH
3.4
O2N COOH
5.3
CH3O NH3+
In
which
of
the
following
acid-‐base
reactions
will
the
equilibrium
favour
the
products
over
the
reactants?
OH + HCO3− O− + H2CO3
1.
COOH NH2 COO
− NH3+
+ +