ASSIGNMENTS
CHAPTER 1- SOLID
STATE
Level
one
Q.1. Why is glass considered
a super cooled liquid?
Q.2 .Why do solids have a
definite volume?
Q.3. Classify the following
as amorphous or crystalline solids: Polyurethane, naphthalene, benzoic
Acid, Teflon, potassium
nitrate, cellophane, polyvinyl chloride, fiber glass, copper.
Q.4. what type of solids are
electrical conductors, malleable and ductile?
Q.5. Name the parameters that
characterize a unit cell.
Q.6. What is meant by the
term 'coordination number'?
Q.7. What is the coordination
number of atoms:
a) In a cubic close-packed
structure?
b) In a body-centred cubic
structure?
Level Two
Q.1. Solid A is a very hard
electrical insulator in solid as well as in molten state and melts at
Extremely high temperature. What type
of solid is it?
Q.2. Ionic solids conduct
electricity in molten state but not in solid state. Explain.
Q.3. Classify the following
as amorphous or crystalline solids: Polyurethane, naphthalene, benzoic acid,
Teflon, potassium nitrate, cellophane, polyvinyl chloride, fiber glass, copper.
Q.4. Define the term
amorphous. Give a few examples of amorphous solids.
Level
three
Q.5. What makes a glass
different from a solid such as quartz? Under what conditions quartz could be converted into glass?
CHAPTER 2-SOLUTIONS
Level One
Q1.What is meant by
semi-molar and deci-molar solutions?
Q2.What will be the mole
fraction of water in ethanol solution containing equal number of moles of water
and ethanol?
Q3.State Roult’s Law in its
general form in reference to solutions?
Q4.How Is colligative
property of the solution when a solute in a solution undergoes:
(i)association
(ii)dissociation ?
Q5.Give one practical
application of depression of freezing point in automobiles.
Q6.Mention one large scale use of the
phenomenon called “Reverse Osmosis”.
Q7.Which one will have
greater boiling point 0.1 M NaCl or 0.1 BaCl2 solutions
in water?
Q8.What will happen to the
vapour pressure of water, if a tablespoon of sugar is added to it?
Q9.Why does the use of
pressure cooker reduce the cooking time?
Q10. The dissolution of
ammonium chloride in water is an endothermic process .What is the effect of
temperature on its solubility?
Q11. Why is liquid ammonia
bottle first cooled in ice before opening it?
LevelTwo
Q1. Out of three solutions
(i) 1M cane sugar solution (ii) 1M NaCl solution (iii) 1M BaCl2 solution,
which one will have
(a)highest boiling point (b)highest freezing point (c)lowest osmotic pressure?
Q2.(a)For which of the
following, the van Hoff factor is not greater than 1?
NaNO3 , BaCl2 , K3Fe(CN)6 , C6H12O6
(b)If glycerine and methyl
alcohol are sold at the same price per kg, which one would be preferred for
use, as an anti-freeze in the car radiators?
Q3.Define Osmotic Pressure.
Arrange the following solutions in increasing order of their osmotic pressure.
urea,sucrose,NaCl,glucose.(if 1g substance is added).
Q4.What is the effect of the
following changes on the osmotic pressure of a solution containing a non-volatile
solute:
(i)Solvent is added to the
solution
(ii)Solute is added to the
solution
(iii)Temperature is raised ?
Q5.Carbon Tetrachloride and
Water are immiscible whereas, ethanol and water are miscible in all proportions.
Co-relate this behavior with molecular structures of these compounds.
Q6.Give reason, why at higher
altitudes, people suffer from a disease called Anoxia.
In this disease, they become
weak and cannot think clearly.
Level Three
Q1.Why do aquatic species
feel more comfortable in lakes in winters than in summers?
Q2. Why is a person suffering
from high blood pressure is adviced to take minimum quantity of
common salt?
Q3. If Kf for water is 1.86˚C/m,
explain why 1 m NaCl in water does not have a freezing point equal
to : (i) -1.86˚C (ii) -3.72˚C
Q4.Derive a relationship
between relative lowering of the vapour pressure and the mole fraction of the
volatile liquid.
Q5. Why dissolution of some
solid compounds is exothermic while that of some others is endothermic?
CHAPTER 3 ELCTROCHEMISTRY
Level One
Q 1 What is the effect of
temperature on molar conductivity?
Q 2 What are the units of
molar conductivity?
Q 3 Name the factors on which
emf of a cell depends.
Q 4 What is the emf of the
cell when the cell reaction attains equilibrium?
Q 5 What is the electrolyte
used in dry cell?
Q 6 How is the cell constant
calculated from conductance value?
Q 7 What flows in the
internal circuit of a galvanic cell?
Q 8 Define electrochemical
series.
Level Two
Q 1 How can you increase
reduction potential of an electrode for the reaction :
Mn+ aq + ne− ⟶ M(s) ?
Q 2 What happens when a piece
of copper is added to (a) an aq solution of FeSO4
(b) aq solution of FeCl3
Q 3 Define corrosion. Write
chemical formula of rust.
Q 4 State Kohlrausch Law. How
do you determine molar conductivity of weak electrolyte at infinite dilution?
Q 5 What is fuel cell? Write
its electrode reaction.
Q 6 Electrolysis OF KBr give
bromine at anode, but KF does not give F2 .
Level Three
Q 1 Write three differences
between potential difference and emf.
Q 2 How many grams of sodium
will be deposited at cathode by passing 10 A current for 10 s
through the electrolysis of
NaCl.
Q 3 The resistance of a
conductivity cell containing 0.001 M KCl solution at 298 K is 1500 Ξ©. What is the
cell constant if conductivity of 0.001 M KCl solution at 298 K is 0.146 × 10-3 S cm-1.
Q 4 Calculate maximum work
done that can be obtained from the following cell under standard
conditions at 250C
ππ π | ππ2+ ∥ πΆπ’2+ ππ |πΆ(π )
πΈ0πΆπ’2+/πΆπ’= 0.34 π£, πΈ0ππ2+//ππ= −0.76 π£
ASSIGNMENTS
(Answers)
CHAPTER
1- SOLID STATE
Level one
Ans.1. Glass is an amorphous
solids, it has tendency to flow but very slowly. This is the cause that glass is
considered as super cooled liquid.
Ans.2. The intermolecular
force of attraction make the particles of solid closely packed and force them
To only oscillate at their
fixed positions. These give solids a definite volume.
Ans.3.Polyurethane, Teflon,
cellophane, polyvinyl chloride, fiber glass – Amorphous solids
Naphthalene, benzoic acid,
potassium nitrate, copper – Crystalline solids.
Ans.4. Metallic solids are
conductor of electricity, malleable and ductile.
Ans.5.Unit cells are
characterize on six parameters – dimensions along three edges and three angles between their edges, i.e. a, b, c which are edges and Ξ±, Ξ² and Ξ³ which are angles between the edges.
Ans.6. Coordination number: -
it is the total number of surrounding atoms of any constituent particle present
in the crystal lattice.
Ans.7. The coordination
number of atoms
a) In a cubic close-packed
structure is 12
b) In a body-centred cubic
structure is 8
Level Two
Ans.1.Given
solid ‘A’ is a covalent solids, such as diamond.
Ans.2. Ionic solids conduct
electricity because of movement of their ions. In solid state ions present in ionic
solids do not move hence do not conduct electricity while in molten state ions
can move and thus conduct electricity.
Ans.3.Polyurethane, Teflon,
cellophane, polyvinyl chloride, fiber glass – Amorphous solids
Naphthalene, benzoic acid,
potassium nitrate, copper – Crystalline solids.
Ans.4.
Amorphous
solids exhibits following properties: -
• Their
constituent particles are of irregular shapes and have short range order.
• They
are isotropic in nature and melt over a range of temperature. Because of which
they
are also known as pseudo solids or
super cooled liquids.
• When
cut with a sharp-edged tool, they cut into two pieces with irregular surfaces.
• They do
not have definite heat of fusion.
• Examples
- glass, rubber, plastic etc.
Level three
Ans.5.
The
arrangement of the constituent particles is different in glass & quartz. In
glass, the
Constituent
particles have short range order whereas in quartz, the constituent particles have both long range as well as
short range orders. We can convert Quartz into glass by heating and then cooling it rapidly.
CHAPTER
2-SOLUTIONS
Level One
Ans.1.Semi molar means
M/2,i.e.,half mole of the solute is present in 1 liter of the solution.
Dec molar means M/10,i.e.,one-tenth mole of
the solute is present in 1 liter of the solution.
Ans.2. 0.5
Ans.3. The relative lowering of the vapour pressure
is equal to the mole fraction of the solute.
Ans.4. (i) Value of
colligative property decreases.
(ii)Value of colligative property
increases.
Ans.5. The use of anti-freeze
(ethylene glycol) in car radiators.
Ans.6. In the Desalination of
Sea water.
Ans.7. 0.1 M BaCl2.
Ans.8. The vapour pressure of
water will decrease as the addition of a non-volatile solute lowers the vapour pressure of the solvent.
Ans.9.At higher pressure over
the liquid (due to increase in pressure of cooker ,the liquid boils at higher
temperature. Therefore, cooking occurs faster.
Ans.10. Since the dissolution
of NH4Cl in water
is an endothermic process, its solubility increases with the rise in
temperature (Le-Chatelier principle)
Ans.11. At room temperature
the vapour pressure of liquid ammonia is very high. On cooling, vapour pressure
decreases. Therefore, the liquid ammonia will not splash out.
Level Two
Ans.1. (a) highest boiling
point -1M BaCl2 solution
(b) Highest freezing point 1M cane
sugar solution
(c) Lowest osmotic pressure -1M cane
sugar solution
Ans.2. (a) C6H12O6
(b) Methyl alcohol
Ans.3. Osmotic Pressure is
defined as the hydrostatic pressure built up on the solution which, just, stops
the flow of solvent.
Sucrose < Glucose < Urea
< NaCl
Ans.4. (i) Decreases
(ii)Increases
(iii) Increases
Ans.5. CCl4 does
not form hydrogen bond with water, while ethyl alcohol forms hydrogen bond with
water.
Ans.6. At higher altitudes,
the partial pressure of oxygen is less than that at the ground level. This leads
to low concentration of oxygen in the blood and the tissues of the people
living in the higher altitudes. As a result of low oxygen in blood, the people
become weak and are unable to think clearly. These are the symptoms of the
condition, known as Anoxia.
Level
Three
Ans.1. Aquatic species
require dissolved O2 for breathing. As solubility of gases decreases with
increase in temperature, less
oxygen is available in summer than winter. Hence, they feel more
comfortable in winters (low
temperature) when the solubility of O2 is
higher.
Ans.2. Osmotic pressure is
directly proportional to the concentration of the solutes. Our body fluids
contain a number of solutes.
If a person takes more salt, the concentration of Na+ and Cl- ions
entering the body fluid ,
raises the concentration of the solutes. As a result, osmotic pressure
increases which may rupture
the blood cells.
Ans.3.
(i) There are two moles if
ions per mol of NaCl. Therefore, ΞTf cannot
be equal to 1.86 and freezing point cannot be equal to 0 - 1.86 = -1.86.
(ii) ΞTf cannot
be equal to 2×1.86 = 3.72 and freezing point = -3.72 because there are strong
interionic attractions for 1m
solution so that the degree of ionization is not 100% at the freezing
point . The value of I is
somewhat less than 2.
Ans.4. According to Roult’s Law , (po -ps )/ po =x2 (mole
fraction of the non-volatile solute)
Mole fraction of the volatile
liquid, x1 =1- x2 or x2 =1- x1 therefore,
(po
-ps )/ po=1- x1 or x1=1- (po -ps) / po = ps/ po
Ans.5. If solute-solvent
interactions are stronger than the solute- solute or solvent- solvent
interactions, energy
is released and the
dissolution is exothermic. And if solute-solvent interactions are weaker than
the solutesolute
or solvent- solvent
interactions, energy is absorbed and the dissolution is endothermic.
CHAPTER
3 ELCTROCHEMISTRY
Level One
Ans.1. Molar conductivity of
an electrolyte increases with increase in temperature.
Ans.2. cm2ohm-1mol-1 or S Cm2mol-1
Ans.3. nature of reactants,
concentration of solution, temperature, pressure of gas.
Ans.4. zero
Ans.5. a paste of NH4Cl, MnO2 and
Carbon
Ans.6. cell
constant= Specific conductance/
Ans.8.The arrangement of
various electrodes in the decreasing or increasing order of their standard reduction
potential.
Level
Two
Ans.1. (i) Increase in
concentration of Mn+ ions in solution.
(ii) By increasing the temperature.
Ans.2. (a) nothing will
happen when the piece of copper is added to FeSO4 solution
because reduction potential of copper is more than reduction potential of iron.
(b) Copper will dissolve in
aq. Solution of FeCl3 because reduction potential of iron is more than
reduction potential of copper.
Ans.3. Corrosion is a process of determination of metal as a result of its reaction with air and water and surroundings. It is due to formation of sulphide, oxide, carbonate and hydroxide. Formula of rust is Fe2O3.xH2O
Ans.4.Molar conductivity of
strong electrolytes at infinite dilution is the sum of two values one
depending upon cation and
other on the anion. Using Kohlraush law we can determine molar
conductivity of weak
electrolyte at infinite dilution.
Ans.5. The device which
converts chemical energy of fuel into electrical energy is called fuel cell.
2π»2 + 4ππ»− ⟶ 4π»2π + 4π
2π»2π + 2π»2 + 4π ⟶ 4ππ»−
__________________________
2π»2 + π2 ⟶ 22π»2π
Ans.6. Oxidation takes place
at anode. Now higher the oxidation potential easier to oxidise. Oxidation
potential of π΅π−, π»2π, πΉ− are in
the following order.
π΅π− > π»2π > πΉ−
Therefore in aq. Solution of
KBr gives Br2 at anode, but KF give oxygen O2 instead
of F2.
Level
Three
Ans.1. E.M.F POTENTIAL
DIFFERENCE
(i)Potential difference of
two electrodes when no current is flowing through
circuit. Potential difference
between electrode in closed circuit.
(ii)It is maximum voltage
obtained from a cell. It is less than maximum voltage obtained
from cell.
(iii)It is responsible for
steady flow of current. It is not responsible for steady flow of
current.
Ans.2. m = zct
= 23×10×10/96500
= 23/965 g sodium
= 0.024 g sodium (approx.)
Ans.3. Conductivity = 1/R ×
cell constant
cell constant = R × conductivity
= 1500 ×
0.146 × 10-3 cm-1
Ans.4 0ππππ = πΈ0πΆπ’ 2+πΆπ’− πΈ0πΆπ’ 2+πΆπ’
= 0.34 – ( – 0.76)
= 0.34 + 0.76
= 1.10 v
△ πΊ0 = −ππΉπΈ0ππππ
= −2 × 96500 × 1.10 = −212300 π½
= −212.3 ππ½
