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Chemistry
Solutions
NCERT Solutions
NCERT Solutions
Solutions
41 Solutions
Q1
Exercises
Define the term solution. How many types of solutions are formed? Write briefly about each type with an example.
Q2
Exercises
Give an example of a solid solution in which the solute is a gas.
Q3
Exercises
Define the following terms:
(i)
Mole fraction
(ii)
Molality
(iii)
Molarity
(iv)
Mass percentage.
Q4
Exercises
Concentrated nitric acid used in laboratory work is 68% nitric acid by mass in aqueous solution. What should be the molarity of such a sample of the acid if the density of the solution is 1.504 g mL⁻¹?
Q5
Exercises
A solution of glucose in water is labelled as 10% w/w, what would be the molality and mole fraction of each component in the solution? If the density of solution is 1.2 g mL⁻¹, then what shall be the molarity of the solution?
Q6
Exercises
How many mL of 0.1 M HCl are required to react completely with 1 g mixture of Na₂CO₃ and NaHCO₃ containing equimolar amounts of both?
Q7
Exercises
A solution is obtained by mixing 300 g of 25% solution and 400 g of 40% solution by mass. Calculate the mass percentage of the resulting solution.
Q8
Exercises
An antifreeze solution is prepared from 222.6 g of ethylene glycol (C₂H₆O₂) and 200 g of water. Calculate the molality of the solution. If the density of the solution is 1.072 g mL⁻¹, then what shall be the molarity of the solution?
Q9
Exercises
A sample of drinking water was found to be severely contaminated with chloroform (CHCl₃) supposed to be a carcinogen. The level of contamination was 15 ppm (by mass):
(i)
express this in percent by mass
(ii)
determine the molality of chloroform in the water sample.
Q10
Exercises
What role does the molecular interaction play in a solution of alcohol and water?
Q11
Exercises
Why do gases always tend to be less soluble in liquids as the temperature is raised?
Q12
Exercises
State Henry's law and mention some important applications.
Q13
Exercises
The partial pressure of ethane over a solution containing
6.56
×
10
−
3
6.56 \times 10^{-3}
6.56
×
1
0
−
3
g of ethane is 1 bar. If the solution contains
5.00
×
10
−
2
5.00 \times 10^{-2}
5.00
×
1
0
−
2
g of ethane, then what shall be the partial pressure of the gas?
Q14
Exercises
What is meant by positive and negative deviations from Raoult's law and how is the sign of
Δ
m
i
x
H
\Delta_{mix}H
Δ
mi
x
H
related to positive and negative deviations from Raoult's law?
Q15
Exercises
An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent. What is the molar mass of the solute?
Q16
Exercises
Heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components are 105.2 kPa and 46.8 kPa respectively. What will be the vapour pressure of a mixture of 26.0 g of heptane and 35 g of octane?
Q17
Exercises
The vapour pressure of water is 12.3 kPa at 300 K. Calculate vapour pressure of 1 molal solution of a non-volatile solute in it.
Q18
Exercises
Calculate the mass of a non-volatile solute (molar mass 40 g mol⁻¹) which should be dissolved in 114 g octane to reduce its vapour pressure to 80%.
Q19
Exercises
A solution containing 30 g of non-volatile solute exactly in 90 g of water has a vapour pressure of 2.8 kPa at 298 K. Further, 18 g of water is then added to the solution and the new vapour pressure becomes 2.9 kPa at 298 K. Calculate:
(i)
molar mass of the solute
(ii)
vapour pressure of water at 298 K.
Q20
Exercises
A 5% solution (by mass) of cane sugar in water has freezing point of 271 K. Calculate the freezing point of 5% glucose in water if freezing point of pure water is 273.15 K.
Q21
Exercises
Two elements A and B form compounds having formula AB₂ and AB₄. When dissolved in 20 g of benzene (C₆H₆), 1 g of AB₂ lowers the freezing point by 2.3 K whereas 1.0 g of AB₄ lowers it by 1.3 K. The molar depression constant for benzene is 5.1 K kg mol⁻¹. Calculate atomic masses of A and B.
Q22
Exercises
At 300 K, 36 g of glucose present in a litre of its solution has an osmotic pressure of 4.98 bar. If the osmotic pressure of the solution is 1.52 bars at the same temperature, what would be its concentration?
Q23
Exercises
Suggest the most important type of intermolecular attractive interaction in the following pairs.
(i)
n-hexane and n-octane
(ii)
I₂ and CCl₄
(iii)
NaClO₄ and water
(iv)
methanol and acetone
(v)
acetonitrile (CH₃CN) and acetone (C₃H₆O).
Q24
Exercises
Based on solute-solvent interactions, arrange the following in order of increasing solubility in n-octane and explain. Cyclohexane, KCl, CH₃OH, CH₃CN.
Q25
Exercises
Amongst the following compounds, identify which are insoluble, partially soluble and highly soluble in water?
(i)
phenol
(ii)
toluene
(iii)
formic acid
(iv)
ethylene glycol
(v)
chloroform
(vi)
pentanol.
Q26
Exercises
If the density of some lake water is 1.25 g mL⁻¹ and contains 92 g of Na⁺ ions per kg of water, calculate the molarity of Na⁺ ions in the lake.
Q27
Exercises
If the solubility product of CuS is
6
×
10
−
16
6 \times 10^{-16}
6
×
1
0
−
16
, calculate the maximum molarity of CuS in aqueous solution.
Q28
Exercises
Calculate the mass percentage of aspirin (C₉H₈O₄) in acetonitrile (CH₃CN) when 6.5 g of C₉H₈O₄ is dissolved in 450 g of CH₃CN.
Q29
Exercises
Nalorphene (C₁₉H₂₁NO₃), similar to morphine, is used to combat withdrawal symptoms in narcotic users. Dose of nalorphene generally given is 1.5 mg. Calculate the mass of
1.5
×
10
−
3
1.5 \times 10^{-3}
1.5
×
1
0
−
3
m aqueous solution required for the above dose.
Q30
Exercises
Calculate the amount of benzoic acid (C₆H₅COOH) required for preparing 250 mL of 0.15 M solution in methanol.
Q31
Exercises
The depression in freezing point of water observed for the same amount of acetic acid, trichloroacetic acid and trifluoroacetic acid increases in the order given above. Explain briefly.
Q32
Exercises
Calculate the depression in the freezing point of water when 10 g of
C
H
3
C
H
2
C
H
C
l
C
O
O
H
CH_3CH_2CHClCOOH
C
H
3
C
H
2
C
H
ClCOO
H
is added to 250 g of water.
K
a
=
1.4
×
10
−
3
K_a = 1.4 \times 10^{-3}
K
a
=
1.4
×
1
0
−
3
,
K
f
=
1.86
K kg mol
−
1
K_f = 1.86 \text{ K kg mol}^{-1}
K
f
=
1.86
K kg mol
−
1
.
Q33
Exercises
19.5 g of
C
H
2
F
C
O
O
H
CH_2FCOOH
C
H
2
FCOO
H
is dissolved in 500 g of water. The depression in the freezing point of water observed is 1.0°C. Calculate the van't Hoff factor and dissociation constant of fluoroacetic acid.
Q34
Exercises
Vapour pressure of water at 293 K is 17.535 mm Hg. Calculate the vapour pressure of water at 293 K when 25 g of glucose is dissolved in 450 g of water.
Q35
Exercises
Henry's law constant for the molality of methane in benzene at 298 K is
4.27
×
10
5
4.27 \times 10^5
4.27
×
1
0
5
mm Hg. Calculate the solubility of methane in benzene at 298 K under 760 mm Hg.
Q36
Exercises
100 g of liquid A (molar mass 140 g mol⁻¹) was dissolved in 1000 g of liquid B (molar mass 180 g mol⁻¹). The vapour pressure of pure liquid B was found to be 500 torr. Calculate the vapour pressure of pure liquid A and its vapour pressure in the solution if the total vapour pressure of the solution is 475 Torr.
Q37
Exercises
Vapour pressures of pure acetone and chloroform at 328 K are 741.8 mm Hg and 632.8 mm Hg respectively. Assuming that they form ideal solution over the entire range of composition, plot
p
t
o
t
a
l
p_{total}
p
t
o
t
a
l
,
p
c
h
l
o
r
o
f
o
r
m
p_{chloroform}
p
c
h
l
oro
f
or
m
, and
p
a
c
e
t
o
n
e
p_{acetone}
p
a
ce
t
o
n
e
as a function of
x
a
c
e
t
o
n
e
x_{acetone}
x
a
ce
t
o
n
e
. The experimental data observed for different compositions of mixture is:
100
×
x
a
c
e
t
o
n
e
100 \times x_{acetone}
100
×
x
a
ce
t
o
n
e
0
11.8
23.4
36.0
50.8
58.2
64.5
72.1
p
a
c
e
t
o
n
e
p_{acetone}
p
a
ce
t
o
n
e
/ mm Hg
0
54.9
110.1
202.4
322.7
405.9
454.1
521.1
p
c
h
l
o
r
o
f
o
r
m
p_{chloroform}
p
c
h
l
oro
f
or
m
/ mm Hg
632.8
548.1
469.4
359.7
257.7
193.6
161.2
120.7
Plot this data also on the same graph paper. Indicate whether it has positive deviation or negative deviation from the ideal solution.
Q38
Exercises
Benzene and toluene form ideal solution over the entire range of composition. The vapour pressure of pure benzene and toluene at 300 K are 50.71 mm Hg and 32.06 mm Hg respectively. Calculate the mole fraction of benzene in vapour phase if 80 g of benzene is mixed with 100 g of toluene.
Q39
Exercises
The air is a mixture of a number of gases. The major components are oxygen and nitrogen with approximate proportion of 20% is to 79% by volume at 298 K. The water is in equilibrium with air at a pressure of 10 atm. At 298 K if the Henry's law constants for oxygen and nitrogen at 298 K are
3.30
×
10
7
3.30 \times 10^7
3.30
×
1
0
7
mm and
6.51
×
10
7
6.51 \times 10^7
6.51
×
1
0
7
mm respectively, calculate the composition of these gases in water.
Q40
Exercises
Determine the amount of
C
a
C
l
2
CaCl_2
C
a
C
l
2
(i = 2.47) dissolved in 2.5 litre of water such that its osmotic pressure is 0.75 atm at 27°C.
Q41
Exercises
Determine the osmotic pressure of a solution prepared by dissolving 25 mg of
K
2
S
O
4
K_2SO_4
K
2
S
O
4
in 2 litre of water at 25°C, assuming that it is completely dissociated.
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