12th_std_chemistry notes of lesson_- 3 mark

1 BHARATHIDHASANAR MATRIC.HR.SEC SCHOOL-ARAKKONAM -12th CHEMISTRY

BHARATHIDHASANAR MATRIC HR.SEC.SCHOOL

ARAKKONAM

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XXIIII--SSTTDD

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BASED ON

TAMIL NADU TEXT BOOK

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XII TH CHEMISTRY YEAR PLAN & PORTION

2014-15

Unit Test-1

1.Atomic Structure-II 2.Periodic Classification-II

Unit Test -2

3.P-Block Elements

8.Solid State

Unit Test-3

9.Thermodynamics

10Chemical Equilibrium-II

Unit Test-4

15.Isomerism in Organic Compounds

16.Hydroxy Derivatives

Unit Test -5

17.Ethers 4.d-Block Elements

Unit Test -6

5.f-block Elements

6.Co-Ordination and its compounds

7.Nuclear Chemistry


Unit Test -7

11.Chemical Kinetics-II 12.Surface Chemistry

Unit Test -8

13.Electro Chemistry –I

18.Carbonyl Compounds

Unit test – 9

19.Carboxylic Acid

20.Organic Nitrogen Compounds.

Unit Test – 10

14.Electro Chemistry-II

21.Biomolecules

22.Chemistry in action


MONTHLY EXAMS AND PORTION

Monthly Exam – 1

1.Atomic Structure-II

2.Periodic lassification-II

3.P-Block Elements

8.Solid State

9. Thermodynamics

15.Isomerism in Organic

Compounds


Monthly Exam – 2

4. d-Block Elements 5. f-block Elements

11.Chemical Kinetics-II

12.Surface Chemistry


19.Carboxylic Acid


Quarterly Exam

1.Atomic Structure-II

2.Periodic classification-II

3.P-Block Elements

4.d-Block Elements

8.Solid State

9.Thermodynamics

10.Chemical equilibrium-II

11.Chemical Kinetics-II

15.Isomerism in Organic

Compounds



19.Carboxylic Acid


Monthly Exam – 3

f-Block Elements

Co-Ordination Compounds

Surface Chemistry

Electro Chemistry-I

Organic Nitrogen Compounds

Monthly Exam-4

Co-Ordination Compounds

Nuclear Chemistry

Electro Chemistry-II

Bio Molecules

Chemistry in Action

Half Yearly Exam Full Portion


3 Marks

1.Atomic Structure -II

THREE MARKS.

1.What do you understand by the dual character of matter?

The idea of deBroglie wave nature waves or deBroglie matter

waves is

based on the fact that light has both wave and particle nature.

Hence particle like

electron or proton can also be considered to be ‘particle’ with

‘wave nature’.

On the other hand, light had been considered to be

electromagnetic waves.

However, after the discovery of light quanta (photons), it

was clarified that the light has wave nature at one time and

particle nature at another time. Therefore, light has a kind of

duality.

2.State Heisenberg‘s uncertainty principle;

“it is impossible to measure simultaneously both the

position

and velocity (or momentum) of a microscopic particle

with absolute

accuracy or certainty.

3.Define an orbital;


An orbital is the region of space around the

nucleus within which the

probability of finding an electron of given energy is maximum

.The shape of this

region (electron cloud) gives the shape of the orbital

4.What are molecular orbitals

In a molecule, electrons are present in new orbitals

called molecular orbitals

Two atomic orbitals can combine to form two

molecular orbitals. One of

these two molecular orbitals one has a lower energy and

the other has a

higher energy. The molecular orbital with lower energy

is called bonding

molecular orbital and the other with higher energy is

called anti bonding

molecular orbital.

5.Why He2 is not formed?

As the bond order for He2 comes out to be zero, this molecule

does not exist.

6.What is bond order?


Bond order may be defined as half the difference between the

number of electrons in bonding molecular orbital‘s (Nb) and

the number of electrons in anti bonding molecular orbital‘s

(Na) i.e.,

Bond Order = 1/2(Nb - Na )

7.Define hybridisation.

Hybridization is the concept of intermixing of the orbitals of

an atom having

nearly the same energy to give exactly equivalent orbitals with

same energy, identical

shapes and symmetrical orientations in space.

The new equivalent orbitals formed are known as the hybrid

orbitals or

hybridized orbitals. Hybrid orbitals have properties entirely

different from the

properties of the original orbitals from which they have been

obtained.


2.PERIODIC CLASSIFICATION - II

1.Mention the disadvantage of Pauling and Mulliken scale.

Although Mulliken‘s scale is less empirical than Pauling

Scale, yet it suffers

from a serious disadvantage that electron affinities with the

exception of a few

elements are not reliably known.

2.Why EA of fluorine is less than that of chlorine?

On moving down a group the electron affinity decreases.

Thus, the electron

affinity of Cl should be less than F. But actually the electron

affinity of

F (320 kJ mol-1) is less than Cl (348 kJ mol-1). The reason

for this is probably

due to small size of fluorine atom. The addition of an extra

electron produces

high electron density which increases strong electron-electron

repulsion. The

repulsive forces between electrons results in low electron

affinity

3.Why the I.E of Ne is greater than that of F

The I.E of Ne is greater than that of F. It can be explained as

follows:

The nuclear charge of Ne (Z = 10) is more than that of F (Z =

9). Greater

the nuclear charge, greater would be the force of attraction

between nucleus and


outermost electron. Hence, the first I.E. of neon would be

greater than that of

fluorine.

4. I.E. of fluorine is more than that of oxygen.Why?

I.E. of fluorine is more than that of oxygen. It can be

explained

as follows.

(i) F (Z = 9; 1s2 2s2 2px2 2py2 2pz

1) is having more nuclear charge than

oxygen (Z = 8; 1s2 2s2 2px2 2py12pz

1). In both the cases, the electron has to be

removed from the same 2p-subshell. As fluorine is having

more nuclear charge

than oxygen, it means that the nucleus of fluorine will attract

the outer 2p-electrons

more firmly than oxygen. Hence, first I.E. of fluorine would

be more than that of

oxygen.

5.I.E of C is More than B.explain

The I.E. of carbon (At. No.6) more than that of boron (At.

No.5)

Reason: Carbon (Z = 6; 1s2 2s2 2px1 2py1 2pz0) is having

more nuclear

charge than boron (Z = 5; 1s2 2s2 2px1 2py02pz0). In both

the cases, one has to

remove electron from same 2p-subshell. Carbon is having

more nuclear charge

than boron. Therefore the nucleus of carbon, attracts the outer

2p-electron more


firmly than does boron. Thus, first I.E. of carbon would be

more than that of

boron

6.Calculate the effective nuclear charge experienced by the 4s

electron in potassium atom.

Solution

The electronic configuration of K atom is

K19 = (1s2) (2s2 2p6) (3s2 3p6) 4s1

Effective nuclear charge (Z*) = Z – S

Z*= 19 – [(0.85 No. of electrons in (n –1)th shell) +

(1.00 total number of electrons in the inner shells)]

= 19 – [0.85 (8) + (1.00 10)]

Z*= 2.20

7.Explain Electron affinity. Electron affinity or electron gain enthalpy is the amount of

energy released

when an isolated gaseous atom accepts an electron to form a

monovalent gaseous

anion.

Atom+ Electron →Anion+ Energy


P-Block Elements

1.Prove that phosphorus acid is a powerful reducing agent?

It is a powerful reducing agent because it has P-H bond.

It reduces silver nitrate solution into silver.

2AgNO3+H2O+ H3PO3 → 2Ag+ H3PO4 + 2HNO3

2.What is Plumbo solvency?

Lead is not attacked by pure water in the absence of air,

but water containing dissolved air has a solvent action on

it due to the formation of lead hydroxide (a poisonous

substance). This phenomenon is called Plumbo solvency.

2Pb + O2 +2H2O → 2Pb(OH)2

3.Why is HF is not stored in silica or glass bottles? Write the

equations.

It cannot be stored in glass or silica bottles as it attack

silicates and silica

Na2SiO3 + 6HF → Na2SiF6 + 3H2O

SiO 2+ 4HF → SiF4 + 2H2O


4.Illustrate the oxidising power of fluorine.

An important feature of the halogen is their oxidising

property. Which is due to high electron affinity of halogen

atoms. The oxidizing power decreases from fluorine to

Iodine.Fluorine is the strongest

Oxidizing agent. It oxidises other halide ions to

halogens in solution or when dry.

F2 + 2X → 2F- + X2 (X- = Cl-,Br -, I-)

5.Write about the Holme‟s signal?

Containers which have a perforated bottom and a hole at the

top are filled with calcium phosphide and calcium carbide.

These are thrown into the sea, Water enters the container

through the bottom and reacts with calcium carbide and

calcium phosphide to give acetylene and phosphine.

Phosphine gets ignited spontaneously as it comes in contact

with air and also ignites acetylene.Thus a bright red flame is

produced which is accompanied by huge smoke due to

the burning of phosphine.This serves as a signal to the

approaching ships.


6.Write the uses of Helium?

1. Because of its lightness and non- inflammability helium is

used to filling balloons for meteorological observations.

2.Because of its lightness it is used in inflating aeroplane

tyres. 3.A mixture of oxygen and helium is used in the

treatment of asthma

7.How is ( K2SO4.Al2(SO4)3.24H2O) potash alum prepared?

Alunite or alum stone is K2SO4.Al2(SO4)3.4Al(OH)3. It is

finely powdered and boiled with dilute sulphuric acid, the

aluminium hydroxide part changes into aluminium sulphate.

When a little more potassium sulphate in calculated amount

is added, the alum is crystallised.

8. How is phosphoric acid prepared in the laboratory?

Boiling a mixture of red phophorus with 50% nitric acid

in a flask fitted with a reflux condenser on a water bath till no

more oxides of nitrogen are liberated. Iodine acts as a

catalyst. The product is evaporated below 453K and then

cooled in a vaccum desiccator surrounded

by freezing mixture when crystals of orthophosphoric

acid are deposited.

P + 5HNO3→ H3PO4 + 5NO2 + H2O


9. Give three uses of neon.

1.Neon is used in discharge tubes and fluorescent bulbs

for advertisement display purposes.

2.Mixed with helium it is used to protect electrical

instruments from high Voltages.

3.Neon light is used in botanical gardens as it stimulates

growth and helps the formation of chlorophyll.

10. What are interhalogen compounds? Give the

preparation of any one.

Each halogen combines with another halogen to form

several compounds known as interhalogen compounds.

They can all be prepared by direct combination or by the

action of a halogen on a lower interhalogen, the product

formed depends on the conditions.

Cl2 + F2 (equal volume) → 2ClF ( Ax Type)

11.What is inert pair effect?

One of the familiar characteristic of p-block elements is to

show inert pair effect that is the tendency of being less

availability for ns electron in bonding. The inert pair effect

increases down the group with the increase in atomic

number.


12.What is the action of heat on phosphorus acid?

When it is heated it undergoes auto-oxidation and

reduction to form phosphoric acid and phosphine.

4H3PO3 → 3H3PO4 + PH3

13. H3PO3 diprotic why?

It is a dibasic acid and gives salts of two types.

ii) H3PO3 + NaOH→ NaH2PO3 + H2O

ii) H3PO3 + 2NaOH →Na2HPO3 + 2H2O

Sodium dihydrogen phosphite Disodiumhydrogen phosphate

4. d - BLOCK ELEMENTS

1. What are ―d‖-block elements?

In these elements, the last electron enters the d orbital of the

penultimate Shell i.e. the last electron goes to (n-1) d orbital.

Hence these elements are named as d-block elements. These

elements have partly filled d-sub shells in their elementary

form or in their simple ions. The d-block elements are called

transition elements because these represent a transition from

highly electropositive elements (metals) of s-block to least

electropositive elements (non-metals) of p-block.

2. How d-block elements are classified?

Based on whether the last electron goes to 3d,4d,5d or 6d

orbital, d-block

elements are classified into four series. They are

i) 3d series or First transition series (21Sc to 30Zn)


ii) 4d series or Second transition series (39Y to 48Cd)

iii) 5d series or Third transition series (57La and 72Hf to

80Hg)

iv) 6d series or Fourth transition series (89Ac and 104Rf to

112) or Incomplete series

3. Explain why d-block elements exhibit variable oxidation

states?

All transition elements exhibit variety of oxidation states

(or) variable valencies

in their compounds. This property is due to the following

reasons.

i) These elements have several (n – 1) d and ns electrons.

ii) The energies of (n – 1)d and ns orbitals are fairly close to

each other.

4. Why transistion elements form complexes?

i) Small size and high positive charge density.

ii) Presence of vacant (n-1)d orbitals which are of appropriate

energy to accept

lone pair and unshared pair of electrons from the ligands for

bonding with

them.

5.Why Zn2+ salts are white while Ni2+ salts are coloured?

Zinc ion has absence of unpaired electron while nickel

ion has unpaired electron so due to his reason nickel ion has

exist in colour.

6. [Ti (H2O)6]3+ is coloured while [Sc (H2O)6]3+ is

colourless. Explain.


Sc ion has absence of unpaired electron while Ti ion has

unpaired electron so due to his reason nickel ion has exist in

colour.

7.Explain Why Mn2+ is more stable than Mn3+.

Electronic configuration of Mn2+ is :[Ar] 3d5 and Mn3+ is:

[Ar] 3d4 Mn2+ has 3d5 electrons and d- sub-level is half

filled. Mn3+ has 3d4 electrons and d-sub-level is neither half

filled or completely filled. Half filled sub-level is more stable

due to symmetry. Therefore Mn2+ is more stable than

Mn3+.

8.A substance is found to have a magnetic moment of

3.9BM. How many unpaired electrons does it contain?

The magnetic moment μ = n( n 2) BM n = number of

unpaired electrons.

3.9 = n( n + 2) ; 3.9 = n( n + 2) ; (3.9)2 = n (n+2)

15 = n2 + 2n ; n2+2n-15=0 ; Solving this equation n = 3

9.Why do transition elements form complexes?

i) Small size and high positive charge density.

ii) Presence of vacant (n-1)d orbitals which are of

appropriate energy to accept lone

pair and unshared pair of electrons from the

ligands for bonding with them.


10. Give any two evidences for the oxidizing nature of

potassium dichromate.

K2Cr2O7 + 7H2SO4 + 6KI→ 4K2SO4 + Cr2(SO4)3 + 3I 2 + H2O

It oxidizes potassium iodide to iodine

K2Cr2O7 + 7H2SO4 + 6FeSO4→ K2SO4 + Cr2(SO4)3 +

3Fe 2(SO4)3 + 7H2O

It oxidizes ferrous sulphate to ferric sulphate

11.Why do d-block elements have variable oxidation states.

Give reason.

i) These elements have several (n-1)d and ns

electrons.

ii) The energies of (n-1)d and ns orbitals are fairly

close to each other.

12.How is chrome-plating done?

i) The articles to be plated with chromium: Cathode

ii) plate of lead : Anode

iii)Electrolytic bath contain : Chromic acid and Sulphuric

acid. During electrolysis chromium deposits on the article.

Generally the articles are first plated

with nickel and then subjected to chromium plating.


13. Write the action of aqua regia on gold.

Gold dissolves in aquaregia (3parts of Con.HCl+1part of

Conc.HNO3) to form auric chloride.

2Au + 9HCl + 3HNO3 2AuCl3 + 6H2O + 3NOCl

14.What is spitting of silver? How can be it prevented?

Molten silver absorbs about twenty times its volume of

oxygen which it again expels on cooling. Globules of

molten silver are thrown off. This is called “Spitting of silver”.

This can be prevented by covering the molten metal with a

layer of charcoal.

f-block elements

THREE MARKS;

1.What are inner transition ( f-block) elements? Give two

examples

The elements in which the extra electron enters ( n- 2 )f

orbital‘s are called

f- block elements. These elements are also called as inner

transition elements

because they form a transition series within the transition

elements. The f-block

elements are also known as rare earth elements. These are

divided into two

series.


i) The Lanthanide series (4f-block elements)ii) The

Actinide series (5f- block elements )

2What is the difference in the electronic configuration of

transition and innertransition

elements?

The electronic configuration of Lanthanides are, The fourteen

electrons are filled in Ce to Lu with configuration [54 Xe

]4f1-14

5d1 6s

2.

The general electronic configuration of transition elements is

(n-1)d1-10

ns1-2.

3.What are lanthanides? Give the various oxidation states of

lanthanides.

The common oxidation state exhibited by all the lanthanides

is +3 (Ln3+) in

aqueous solutions and in their solid compounds. Some

elements exhibit +2 and

+4 states as uncommon oxidation states

La - +3

Ce - +3, +4, +2

Pr - +3, +4

Nd - +3, +4, +2

4. What are mish metals? Give their uses

Alloys of Lanthanides are known as mish - metals .The major

constituents


of mish-metals are Ce(45-50%), La(25%), Nd(5%) and small

quantities

of other lanthanide metals and Fe and Ca impurities. Mish-

metals are used

for the production of brands of steel like heat resistant,

stainless and

instrumental steels. Mg- alloys containing 30% mishmetal and

1% Zr are

useful in making parts of jet engines

5. Write the uses of Lanthanides and Actinides

LANTHANIDES USES

1. A pyrophoric alloy which contains cerium, lanthanum and

Neodymium; iron;

aluminium; calcium, carbon and silicon is used in cigarette

lighters, toys,

flame throwing tanks and tracer bullets.

2. Ceria (CeO2) and thoria (ThO2) are used in gas lamp

materials.

ACTINIDES USES

1.U-235 is fissionable, it is used as fuel in nuclear power

plants and as a

component in nuclear weapons

2.Plutonium - 238 is used as a power source in long mission

space probes.


6. Coordination Compounds and

Bio-Coordination Compounds

1.What are simple salts? Give one example

A simple salt is formed by the neutralisation of an acid by a

base.

KOH+ HCl KCl+H2O

Normally, a simple salt ionises in water and produces ions in

solution. The solution of the simple salt exhibits the properties

of its component ions

2.What are double salts? Give one example.

These are molecular compounds which are formed by the

evaporation of solution containing two (or) more salts in

stoichiometric proportions. Hence the molecular compounds

which dissociate in solution into its constituent ions are

known as double salt. Double salts retain their properties only

in solid state. They are also called as lattice compounds

Example;

K2SO4 . Al2(SO4)3 . 24H2O-Potash alum

FeSO4 . (NH4)2 SO4. 6H2O-Mohr‘s salt

3.In what way complex salt differs from double salt?

The molecular compounds, do not dissociate into its

constituent ions in solution are called coordination

compoundthe individual components lose their identity.

The metal of the complex ion is not free in solution

unlike metal in double salt in solution in this way co


ordination complex ion is differnce from doublt salt

solution.

4.What are ligands and coordination number?

A ligand is an ion (or) a molecule capable of functioning

as an electron donor. Therefore the neutral molecules or

ions which are directly attached to the central metal ion

are called as ligand (or) coordination groups

The coordination number of a metal ion in a complex can

be defined as the number of ligand donor atoms to which

the metal is directly bonded. Numerically coordination

number represents the total number of the chemical

bonds formed between the central metal ion and the

donor atoms of the ligands. For example in K4[Fe(CN)6]

the coordination number of Fe(II) is 6 and in

[Cu(NH3)4]SO4 the coordination number of Cu(II) is 4.

5.Give one example for a monodentate ligand, a bidentate

ligand and a chelating

ligand.

MONODENTATE LIGAND;

F--Fluoro, Cl—Chloro CN—Cyano

BIDENTATE LIGAND

NH2 - CH2 - CH2 – NH2 .C2O4—Oxalato

Chelating ligand.;

If a ligand is capable of forming more than one bond with the

central metal atom (or) ion then the ring structures are


produced which are known as metal chelates. Hence the ring

forming group are described as chelating agents (or)

polydentate ligands.

6.Calculate the charge on the central metal ion present in the

following

complexes.

[Fe(NH3)4Cl2] NO3 Na[B(NO3)4]

7.Name the following complexes

[Co(NH3)5(H2O)]Cl3 Na[B(NO3)4]

8.Write the formula structure of the following

a) tris(ethylenediamine)cobalt(III) ion

b) pentaamminesulphatocobalt(III) chloride

9.Draw the structure of cis and trans-[Pt(NH3)2Cl2]

10.What are chelates? Give one example

If a ligand is capable of forming more than one bond with the

central metal atom (or) ion then the ring structures are

produced which are known as metal chelates. Hence the ring

forming group are described as chelating agents (or)

polydentate ligands.


7.NUCLEAR CHEMISTRY

1.Define radio activity.

The phenomenon of spontaneous disintegration of certain

atomic nuclei resulting in the emission of radioactive rays is

called radioactivity.

Radioactivity is a nuclear phenomenon and it is not affected

by external

factors such as temperature, pressure etc. This phenomenon

was discovered

by Henry Becqurel.

2.What is half life period.

The time required to disintegrate one half of any radioactive

substance is called half life period (t½). The half life period

(t½) of a

radioactive substance is independent of initial concentration.

It depends only

on the disintegration constant of the radioactive element. t½

is used to

indicate the relative stability of radioactive substance. If t½ is

the shorter,

faster is the rate of decay and hence the substance is more

unstable and


viceversa.

3.Write two difference between chemical reaction and nuclear

reaction

CHEMICAL

REACTIONS

NUCLEAR REACTIONS

These reaction involve

some loss,

gain or overlap of outer

orbital

electrons of the reactant

atoms.

Nuclear reactions involve

emission of

alpha, beta and gamma

particles from

the nucleus.

A chemical reaction is

balanced in

terms of mass only

Nuclear reaction is balanced

in terms

of both mass and energy.

The energy changes in any

chemical

reaction is very much less

when

compared with nuclear

reaction.

The energy changes are far

exceed

than the energy changes in

chemical

reactions.

In chemical reactions, the

energy is

expressed in terms of

kilojoules per

mole.

In nuclear reactions, the

energy

involved is expressed in

MeV (Million

electron volts) per individual

nucleus.

4.What is Q value of a nuclear reaction?


The amount of energy absorbed or released during nuclear

reaction is called

Q-value of nuclear reaction

In the case of energy absorbed then mp>mr, then Q value will

be positive. Q value of a nuclear reaction in the case of energy

released = (mp–mr) 931 MeV. In the case of energy released,

mr>mp, and hence Q value will be negative.

5.Explain the principle behind the Hydrogen bomb.

The highly destructive hydrogen bomb is also based on the

fusion reactions of hydrogen to form helium producing large

amount of energy. Hydrogen bomb consists of an arrangement

for nuclear fission in the centre surrounded by a mixture of

deuterium (1H2) and lithium isotope (3Li6). Fission reaction

provides the high temperature necessary to start the fusion.

6.What is Radio carbon dating?

This method was developed by Willard and Libby to

determine the age of wood or animal fossils. This method is

based on the fact that 6C14, radioactive isotope of carbon is

formed in the upper atmosphere by reaction with neutrons

(from cosmic rays).

7N14 + 0n1 6C14 + 1H1

The C14 atoms thus produced are rapidly oxidised to 14CO2

which in turn is Incorporated in plants as result of

photosynthesis. Animals too consume C14 byeating plants.

On death, organisms cease to take in fresh carbonations.

Carbon-14 begins to decay.

6C14 7N14 + -1e0

6.State two uses of radio carbon dating.


Carbon dating has proved to be a great tool for

correlating facts of historical importance.

It is very useful in understanding the evolution of life,

and rise and fall of civilizations.

8.SOLID STATE - II

1.Define the terms; space lattice and unit cell

Unit cell is the smallest fundamental repeating portion of a

crystal lattice

from which the crystal is built by repetition in three

dimension.

2.State Bragg‘s law.

3.What are superconductors?


4.How crystals are classified?

5.Give example for molecular and ionic crystals

6.What is a vitreous state?

The State Which Exist, Lying Between Solid and Liquid is

called as Vitreous state. Ex. Glass

7.Give two example for AB and AB2 type ionic crystals

8.What is imperfection in solids?

Almost all the crystals encountered in practice suffer from

imperfections or

defects of various kinds. An ideally perfect crystal is one

which has the same unit


cell and contains the same lattice points throughout the

crystal. The term

imperfection or defect is generally used to describe any

deviation of the ideally

perfect crystal from the periodic arrangement of its

constituents.

Point Defects

1. Schottky defects

2. Frenkel defects

10.Write a note on the assignment of atoms per unit cell in fcc

11.Write a short note on metallic crystals

Metallic crystal consists of an assemblage of positive ions

immersed in a sea

of mobile electrons. Thus, each electron belongs to a number

of positive ions and

each positive ion belong to a number of electrons. The force

that binds a metal

ion to a number of electrons within its sphere of influence is

known as metallic

bond. This force of attraction is strong and is thus responsible

for a compact

solid structure of metals.

12.How are glasses formed?


When certain liquids are cooled rapidly there is no formation

of crystals at a

definite temperature, such as occurring on slow cooling. The

viscosity of the

liquid increases steadily and finally a glassy substance is

formed.

9.THERMODYNAMICS – II

1.What is entropy? What are the units of entropy?

Entropy is a measure of randomness or disorder of the

molecules of a system and it is a thermodynamic state

function. The entropy function “S” represents the ratio of

heat involved (q) to the temperature (T) of the process.

SI unit is JK-1

2.What is Gibb’s free energy?

The isothermally available energy in a system is called

Gipps free energy (G). G is defined as H – TS where H and S

are the enthalpy and entropy of the system respectively and

T = temperature.

G = H - TS

3. What types of liquids or substances deviate from

Trouton‟s rule?

i)Low boiling liquids such as Hydrogen and Helium

which boil only a little above 0K.


ii)Polar substances like water, alcohol which form

hydrogen bonded liquids and exhibit very high boiling points

as well as high ∆Hvap.

iii) Liquids such as acetic acid whose molecules are

partially associated in the vapour phase and possess very

low entropy vapourisation which is very much less than 21

cals / mol / deg.

4.Give the Kelvin – Planck statement of second law of

thermodynamics.

“It is impossible to construct an engine which operated

in a complete cycle will absorb heat from a single body and

convert it completely to work without leaving some

changes in the working system

5.State Classius statement of second law of

thermodynamics.

“It is impossible to transfer heat from a cold body to a

hot body by a machine without doing some work”


6.Calculate the molar heat of vapourisation of the ideal

liquid CCl (Bp. of CCl 4 76°C and ∆S=87.864J) ∆Hvap

∆Svap = = 21cal.deg-1mole-1 ; ∆Hvap = ∆Svap X Tb

∆H vap of CCl4 = ∆Svap X Tb = 87.86 X (76 + 273) =

30663.14 J mole-1.

8 . ∆H and ∆S values of a reaction at 300K are -

10K.Cal.Mole-1 and 20 Cal.deg-1mole-1 respectively.

Calculate ∆G value?

∆G = ∆H - T∆S

At 300K ∆G = - 10,000 – 20 X 300

= - 16,000 cals.mole-1.

∆G = - ve , spontaneous reaction.

8.Give entropy statement of second law of

thermodynamics. Write unit of entropy also.

“A process accompanied by increase in entropy tends to be

spontaneous

Unit of entropy : heat x temperature -1 i) calories per

degree per mole ii)cgs unit of entropy = calk-1 iii) eu per

mole iv) SI unit is JK-1


13 What are spontaneous reactions?

The term „natural process‟ means that the process is

spontaneous and does not need to be induced. It takes place

on its own accord. In order to find out whether a process is

spontaneous or not, the entropy changes of the system and

the surrounding for the stipulated process is considered.

∆S = +ve , the entropy of the universe increases.

10.Chemical Equilibrium

1.In the equilibrium H2 +I2 →2HI the number of moles

of H2, I2 and HI are 1,2,3 moles respectively. Total pressure

of the reaction mixture is 60 atm. Calculate the partial

pressures of H2, I2 and HI in the mixture.

Solution:

H2 + I2 → 2HI

Number of moles of H2 at equilibrium = 1 mole

Number of moles of I2 at equilibrium = 2 mole

Number of moles of HI at equilibrium = 3 mole


Total number of moles of equilibrium = 1+2+3 = 6 moles

Mole fraction of H2 = 1; Mole fraction of I2 = 2

Mole fraction of HI = 3

Partial pressure = Mole fraction x Total pressure

P = 1x 60 = 10 atm ; P = 2x 60 = 20 atm ; P =3x 60 = 30

atm

2.State Le Chatelier‟s principle.

If a system at equilibrium is subjected to a disturbance

or stress, then the equilibrium shifts in the direction that

tends to nullify the effect of the disturbance or stress.

3.What happens when ∆ng = 0, ∆ng = -ve, ∆ng = +ve in a

gaseous reaction?

The relation between Kp and Kc is

Kp = Kc (RT) ∆ng i) when ∆ng = 0, Kp = Kc

ii) when ∆ng = -ve, Kp < Kc iii) when ∆ng = +ve , Kp>Kc 3


4.Define reaction quotient. How is it related to

equilibrium constant?

Reaction quotient, Q is defined as the ratio of product of

initial concentrations of products to the product of initial

concentrations of reactants under non equilibrium

conditions.

When Q is greater than Kc, (Q>Kc) reverse reaction is

favoured.

When Q is lesser than Kc, (Q<Kc), forward is reaction

favoured.

When Q is equal to Kc , (Q=Kc), reaction is at equilibrium

5.What is the relationship between formation

equilibrium constant and dissociation equilibrium

constant? Give an example.

In a chemical equilibrium reaction, the equilibrium constant

of the dissociation equilibrium reaction which is also known

as dissociation constant is found to be the reciprocal value of

the equilibrium constant for the formation equilibrium

reaction. Formation equilibrium reaction, Dissociation

equilibrium reaction


6.Define equilibrium constant?

The equilibrium constant (Kc) represents the ratio of

product of the molar concentrations of the products to the

product of the molar concentrations of the reactants at

equilibrium condition. The concentration of each species is

raised to the power of number of moles present in the

stoichiometric equation.

7. Dissociation of PCl5 decreases in the presence of increase

in Cl2. Why?

According to Le chatelier principle, increase in

concentration of any one of the reactants or products

shifts the equilibrium more towards the opposite direction.

So by increasing the concentration of Cl2, the equilibrium

shifts in the reverse direction, that is more of PCl5 is

formed. By increasing the presence of Cl2, PCl5 dissociation is

decreased.

12 Why is equilibrium reaction refered to as dynamic

equilibrium?

Chemical equilibrium is dynamic when the

forward and reverse reactions take place endlessly and

simultaneously with equal rates. Rf=Rr


11.CHEMICAL KINETICS

1.Explain Pseudo first order reaction

Thus in a second order reaction, when one of the reactants

concentrationis in excess (10 to 100 times) of the other

reactant, then the reaction follows a first order kinetics and

such a reaction is called pseudo-first order reaction.

In a reaction of the type,

CH3COOCH3 + H2O→ CH3COOH + CH3OH

2. Write Arrhenius equation and Explain The terms

Arrhenius equation is given as

k = A e–Ea/RT

where k = rate constant, Ea = activation energy, A =

frequency factor,

R = gas constant, T = temperature in Kelvin. If k1 and k2 are

the rate constants

measured at two different T1 and T² temperatures respectively

3. Explain threshold energy

threshold energy which is needed to make the collisions

effective and successful. The additional energy required by

the molecules to attain the threshold energy in addition to the

energy of colliding molecules is called as activation energy

‗Ea‘. Thus,

activation energy = threshold energy - Energy of colliding

molecules

4.Explain Half Life Period

Half life period, ‗t½‘, of a reaction is defined as the time

required to reduce the concentration of a reactant to one half

of its initial value. t½ values are calculated by using the

integrated rate equation of any order of a reaction.


5. Explain Consecutive reactions

The reactions in which the reactant forms an intermediate and

the intermediate forms the product in one or many subsequent

reactions are called as consecutive or sequential reactions. In

such reactions the product is not formed directly from the

reactant.

6.Explain Parallel reactions

In these group of reactions, one or more reactants react

simultaneously in two or more pathways to give two or more

products.

7.Explain Characteristics of order of a reaction

(i) The magnitude of order of a reaction may be zero, or

fractional or integral values. For an elementary reaction, its

order is never fractional since it is a one step process.

(ii) Order of a reaction should be determined only by

experiments. It cannot be predicted interms of stoichiometry

of reactants and products.

(iii)Simple reactions possess low values of order like n =0,1,2,

Reactions with order greater than or equal to 3.0 are called

complex reactions. Higher order reactions are rare.

8.What is order of the reaction

The term order can be defined as the sum of the powers

of the exponential powers to which each concentration term is

raised in the experimentally determined rate law of a chemical

reaction.

12.Surface Chemistry

1. Define adsorption.

The process of adsorption of gases by solids is a common

phenomenon.

The charcoal specially coconut charcoal has a great

capacity of the adsorption

of gases. Silica gel is also utilised for the adsorption of

number of gases. The


solid that takes up gas or vapour or solute from a given

solution is called

adsorbent and the solute or gas which is held to surface of

solid is known as

adsorbate.

2. Define colloidal solution.

A colloidal system is made up of two phases. The substance

distributed

as the colloidal particles is called the dispersed phase. The

second continuous

phase in which the colloidal particles are dispersed is called

the dispersion

medium.

3.What is electrophoresis?

If electric potential is applied across two platinum electrodes

immersed

in a hydrophilic sol, the dispersed particles move toward one

or the other

electrode. The movement of sol particles under an applied

electric potential

is called electrophoresis or cataphoresis. If the sol particles

here negatively

charged, they migrate toward the positive electrode. On the

other hand, if

they have positively charged they move toward the negative

electrode. From

the direction of movement of the sol particles, we can

determine the charge

of the sol particles.


2. What is catalysis ?

A catalyst is a substance which alters the speed of a

chemical reaction

without itself undergoing any chemical change and the

phenomenon is known

as catalysis.

3. What are the two types of catalysis

Catalytic reactions are classified into two broad types;

1. Homogeneous catalysis

2. Heterogeneous catalysis

4. What are active centers ?

The catalytic surface has unbalanced chemical bonds on it.

The reactant

gaseous molecules are adsorbed on the surface by these free

bonds. This accelerates the rate of the reaction. The

distribution of free bonds on the catalytic surface is not

uniform. These are crowded at the peaks, cracks and corners

of the catalyst. The catalytic activity due to adsorption of

reacting molecules is maximum at these spots. These are,

therefore, referred to as the active centres. If a catalyst has

more active centres, then its catalytic

activity is increased.

5. Why colloidal system in gas in gas does not exist ?

A colloidal solution of gas in gas is not possible as gases

are completely

miscible and always form true solutions.

8. Why colloids are purified ?

In the methods of preparation stated above, the resulting sol

frequently


contains besides colloidal particles appreciable amounts of

electrolytes. To

obtain the pure sol, these electrolytes have to be removed.

This purification

of sols can be accomplished by three methods:

(a) Dialysis

(b) Electrodialysis and

(c) Ultrafiltration

9. What are emulsions ?

These are liquid-liquid colloidal systems, i.e., the dispersion

of finely

divided droplets in another liquid. If a mixture of two

immiscible or partially

miscible liquids is shaken, a coarse dispersion of one liquid in

the other is

obtained which is called emulsion. Generally, one of the two

liquids is water.

There are two types of emulsions.

10. What is Tyndall effect ?

When a strong beam of light is passed through a sol and

viewed at right

angles, the path of light shows up as a hazy beam. This is due

to the fact that

sol particles absorb light energy and then emit it in all

directions. This

scattering of light illuminates the path of the beam. The

phenomenon of the

scattering of light by the sol particles is called Tyndall effect

13.ELECTRO CHEMISTRY-II

1.Explain laws of faraday


Faraday’s First law :

The mass of the substance (m) liberated at the electrodes

during the

electrolysis is directly proportional to the quantity of

electricity (Q) that

passes through the electrolyte.

Faraday’s Second law :

When the same quantity of electricity passes through solutions

of different

electrolytes, the amounts of the substances liberated at the

electrodes are

directly proportional to their chemical equivalents.

2.Explain Electrochemical equivalent.

Electrochemical equivalent defined in First law

If m is the mass of substance (in grams) deposited on

electrode by passing

Q coulombs of electricity, then

m Q ... First law

64

We know that Q = I t

or m = Z I t

where Z is the constant known as the Electrochemical

equivalent of the

substance (electrolyte). If I = 1 ampere and t = 1 second, then

m = Z

Thus, the electrochemical equivalent is the amount of a

substance

deposited by 1 ampere current passing for 1 second (i.e., one

coulomb)

3.Metallic Conductivity Decreases with increase in

temperature Why?


Conductivity of metal decreases The conductivity of

electrolytes with increase in temperature due increases with

increase in to the enhanced thermal vibration temperature.

This is due to of metal atoms disrupting the increase with

ionic mobility. movement of electrons passing through them.

4.Explain Equivalent conductance

Equivalent conductance : Equivalent conductance (C) is

defined as

the conductance of an electrolyte solution containing one

gram equivalent

of the electrolyte. It is equal to the product of specific

conductance () of the solution and the volume (V) of the

solution that contains one gram equivalent of the electrolyte.

(C) =V In general if an electrolyte solution contains N

gram-equivalents in 1,000 cc of the solution the volume of the

solution containing 1 gram equivalent will be 1000 N 10-6

m3 (1 cc = 10-6 m3)

C = 103 N mho.m2 gm.equiv.-1

for 1 : 1 electrolyte normality N equals to molarity ‗C‘. Then

C =103 C mho.m2.(gm.equiv)-1

C values depend on the type of the electrolyte, concentration

of the solution and temperature.

5.State kohlraush’s law

This law states that, ‗‗at infinite dilution wherein the

ionisation of all electrolytes is complete, each ion migrates

independently and contributes a definite value to the total

equivalent conductance of the electrolyte‘‘.

6.What is Common ion effect?

The reduction of the degree of dissociation of a salt by the

addition of a common-ion is called the Common-ion effect. 7.What is Buffer


A buffer solution is one which maintains its pH fairly constant

even upon the addition of small amounts of acid or base.

In other words, a buffer solution resists (or buffers) a change

in its pH.

15.ISOMERISM IN ORGANIC CHEMISTRY

1.Mesotartaric acid is an optically inactive compound

with asymmetric carbon atoms.Justify your answer.

Meso tartaric acid has two asymmetric carbon atoms,

one asymmetric carbon atom is dextrorotatory and the other

leavorotatory-both rotating to the same extent in opposite

directions. The net result is, that this isomer becomes

optically inactive and is called “Meso” isomer. The optical

inactivity of the „Meso‟ isomer is due to the internal

compensation. It is due to the inherent symmetry in the

molecule.

2.What are the condition for a compound to be optically

active?

i) At least one carbon atom that is bonded to four

different atoms or groups, it is called asymmetric carbon

atom.

ii) Asymmetric molecule is not superimposable on its

mirror image.


iii) Chirality is the essential and the sufficient condition

for a molecule to optically active.

3.Differentiate diasteriomers from enantiomers.

Enantiomer

Diastereomer

1. *Optical isomers having the same magnitude

Differ in the magnitude of optical

but different sign of optical rotation.

rotation.

2 * They have configuration with non-super

imposable object mirror image relationship.

They are never mirror images.

3 * Separation of enantiomers is a tedious process

Separation from the other pairs of enantiomers is easy.

4. What is racemic mixture? Give an example.

When equal amounts of d-isomer and l-isomer are

mixed one gets a “racemic mixture”and this process is called

racemisation.


Ex. d and l - tartaric acid.

5.What are optical isomers? Give an example.

The compounds having same molecular and structural

formula but differ only in magnitude of the optical rotation

are called optical isomers. This phenomenon is known as

optical isomerism. Ex. d-lactic acid and l-lactic acid.

6.Write briefly on „ Racemic mixture‟ with an example.

When equal amounts of d-isomer and l-isomer are

mixed one gets a “racemic mixture” and this process is

called racemisation. Ex. d and l - tartaric acid.

A racemic mixture becomes optically inactive. Because,

in this mixture rotation

towards clockwise direction by the dextro isomer is

compensated by the rotation towards

the anticlockwise direction by the laevo isomers.

7. Trans – isomer is more stable than cis isomer. Why?

In the cis-isomer, similar groups are very near to each

other Vander waals repulsion and steric hindrance make the

molecule much unstable. In the trans-isomer, similar groups


are diagonally opposite to each other. Hence ther is no steric

interaction. Generally trans isomer is more stable than cis

isomer.

17.ETHERS

1.Write the IUPAC names of

(a) C2H5OCH3 methyl ethyl ether

(b) C6H5OC2H5 phenatole (or)ethyl phenyl ether

2.Ethers should not be heated to dryness. Why ?

Because of ether is very explosive even at room temperature

so we should not keep it outside it should be kept on cooling

place only.

3.Ethers are the best solvents of Grignard reagents- Account

for this

statement.


3.Williamson’s synthesis

This is the most important method. It consists of heating alkyl

halides

with sodium or potassium alkoxide

6. Why are ethers not soluble in water ?

ethers are not soluble in water due to absence of hydrogen

bond and organic solvents never miscible with inorganic

solvents.

7. Mention the uses of diethyl ether.

1.Used as anesthetic.

2. Used as a solvent

8. What happens when anisole is treated with Lewis acid ?

9. What happens when anisole is nitrated ?

10.Write equation for the conversion of phenol to anisole


19. CARBOXYLIC ACIDS

1.What is trans – esterification?

In presence of a little acid, methyl acetate is cleaved by

ethyl alcohol to form ethyl acetate.

CH3COOCH3 + C2H5OH →CH3COOC2H5 + CH3OH

2. What is meant by esterification reaction? Write the

equation.

Carboxylic acid reacts with alcohols in presence of

mineral acid as catalyst and forms esters. This reaction is

called esterification.

CH3COOH + C2H5OH → CH3COOC2H5 + H2O

3.Give the source and trivial name of i) HCOOH ii)

C3H7COOH iii) C11H23COOH.

HCOOH

Red ant (formica)

Formic acid

C3H7COOH

Butter (Butyrum)


Butyric acid

C11H23COOH.

Laurel Oil

Lauric acid

4. Mention the uses of oxalic acid.

i) for removing ink stains and iron stains.

ii) as mordant in dyeing and calico printing

iii) in manufacture of ink and metal polishes. iv) Redox

titration.

5.Formic acid reduces Tollen‟s reagent but acetic acid does

not. Give reason.

Formic acid is unique because it contains both an

aldehyde group and carboxyl group also. Hence it can act as a

reducing agent. But acetic acid does not.

6.Write the tests to identify salicylic acid.

i) An aqueous solution of salicylic acid gives violet

colour with neutral ferric chloride.


ii) It gives effervescence with the sodium bicarbonate.

iii) It is soluble in sodium hydroxide and reprecipitated

on acidification.

iv) with bromine water the colour is discharged with the

formation of white precipitate.

7.Account the reducing nature of formic acid with

suitable illustration.

Formic acid is unique because it contains both an

aldehyde group and carboxyl group also.

Hence it can act as a reducing agent. But acetic acid

does not.

Formic acid reduces ammoniacal silver nitrate solution

to metallic silver.

HCOOH + Ag 2O→ H2O + CO2 + 2Ag

8. Write three tests to identify carboxylic acids.

i) Aqueous solution of carboxylic acids turn blue litmus

into red colour.

ii)Carboxylic acids give brisk effervescence with sodium

bi-carbonate due to the evolution of carbon-di-oxide.


iii)On warming carboxylic acids with alcohol and

concentrated sulphuric acid it forms ester which is identified

from its fruity odour.

9. Mention the uses of Benzoic acid.

i) Benzoic acid is used as an urinary antiseptic.

ii) Sodium benzoate is used as food preservative.

iii) It is used for the manufacture of dyes

iv) Benzoic acid vapours are used to disinfect bronchial

tube.

22. BIOMOLECULES

1. What are carbohydrates ? Give two examples

Carbohydrates are polyhydroxy aldehydes or polyhydroxy

ketones. They

are naturally occuring organic substances. They are present in

both plants

and animals. Carbohydrates are formed in the plants by

photosynthesis from

carbon dioxide and water in sunlight

2. Give the structure of sucrose.


3. What is starch ? What are the ultimate hydrolysis products.

Starch is a white amorphous substance with no taste or smell.

Starch is present in wheat, corn, barley, rice, potatoes, nuts,

etc.

4. What is the action of con. HI on glucose ?

22. CHEMISTRY IN ACTION

1. Define chemotherapy.

Treatment of certain diseases by destroying the invading

organism

without damaging the cells of the host, by the use of certain

organic

compounds in known as chemotherapy.

2. What are anaesthetics ? Give one example.

The drugs which produce loss of sensation are called

anaesthetics. They


are classified into two types. (i) General anaesthetics are the

agent, which

bring about loss of all modalities of sensation, particularly

pain along with

‗reversible‘ loss of conciousness. (ii) Local anaesthetics

prevent the pain

sensation in localised areas without affecting the degree of

conciousness.

3. In what way antipyretics are important.

Local anaesthetics prevent the pain sensation in localised

areas without affecting the degree of conciousness

4. Why Iodoform and phenolic solutions are called antiseptic

?

(i) Iodoform, CHI3 is used as an antiseptic and its 1% solution

is a

disinfectant.

(ii) 0.2 percent solution of phenol acts as an antiseptic and its

1% solution

is a disinfectant.

5. Give two examples of anti malarias

quinine, primaquine and chloroquine are some of the best

antimalarials.

6. What are antibiotics ?

Many microorganisms (bacteria, fungi and moulds) produce

certain

chemicals which inhibit the growth or metabolism of some

other

microorganism. Such chemical compounds are known as

antibiotics.


7. In what way antacids are important ?

Certain drug formulations provide relief from such burning

sensation.

These are known as antacids.

Quite often, after eating oily and spicy food, one may feel

uncomfortable

due to some burning sensation in stomach/food pipe. This is

due to the

imbalance in the acidity in the stomach

8. What are antipasmodics ?

There are a group of medicines that include natural bellodona

alkaloids

(atropine, bellodona) .These medicines are used to relieve

cramps, spasms of the stomach,

intestines and bladder. Some are used with antacid, or other

medicine in the

treatment of peptic ulcer. These medicine prevent nausea,

vomiting and

motion sickness. In certain surgical and emergency procedure,

these are

used to help relax stomach and intestine for certain types of

examination or

diagnosis

9. Give any two characteristics of Dye.

(i) It should have a suitable colour.

(ii) It should be able to fix itself or be capable of being fixed

to the fabric.

10. What are chromophores ? Give two examples.


(i) An organic compound appears coloured due to the

presence of certain

unsaturated groups (the groups with multiple bonds) in it.

Such groups with

multiple bonds are called chromophores

11. What are artificial sweetening agents ? Give two

examples.

Mono and disaccharides are sweet in taste. Sweetness is

commonly

associated with sugars. However, certain organic compounds

which have

been synthesized in laboratories are known to be many times

sweeter than

canesugar. Such compounds are called artificial sweetening

agents or

artificial sweetners

12. What is Buna-S ?

12th_std_chemistry notes of lesson_- 3 mark

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