P-Block Elements

Front 1

Elements of Group 15

Back 1

Nitrogen

Phosphorus

Arsenic

Antimony

Bismuth

Hint 1

N

P

..

..

..

Front 2

Chile Saltpetre

Back 2

NaNO3

Front 3

Indian Saltpetre

Back 3

KNO3

Front 4

P block ranges from?

Back 4

Group 13 to 18

Front 5

Group 15 is also called

Back 5

Pnictogens

Front 6

E.C of group 15

Back 6

s orbital is completely filled

ns2np3s orbital is completely filledp orbital is partially filledHence E.C is extra stable

ns2np3s orbital is completely filledp orbital is partially filledHence E.C is extra stable

p orbital is partially filled

Hence E.C is extra stable

Front 7

Atomic Radii grp 15

Back 7

Inc down the grp

Huge inc from N to P

small inc from As->Sb->Bi due to presence of completely filled d and/or f orbitals

Front 8

Ionisation Enthalpy (IE) of grp 15

Back 8

Dec downwards with inc of atomic size

Greater than grp 14 due to stability by half filled p orbitals

1st IE<2nd<3rd

Front 9

Electronegativity of grp 15

Back 9

Dec downwards with inc in atomic size

Front 10

Physical Properties of grp 15

Back 10

All eles are polyatomic

N2-gas rest are solid

Metallic character inc downwards

N,P- non metals

As,Sb- metalloids

Bi- metal

BP inc downwards

MP inc up to As and dec to Bi

Except N all show allotropy

Front 11

OS of grp 15

Back 11

-3,+3 and +5- common OS

-3- dec downwards, Bi hardly forms compound

+5- Dec downwards, Only Bi(V) compound is BiF5

+3- inc downwards due to inert pair effect

Front 12

OS of N

Back 12

+1,+2,+4 with O2

OS from +1-+4 tend to disproportionate in acid sol:

3HNO2--> HNO3+ H2O+2NO

Front 13

OS of P

Back 13

+1 and +4 OS in some oxoacids

All intermediate OSs disproportionate into +5 and -3 in both alkali and acid

Front 14

Anomalous behavior of N?

Back 14

Small size

High electronegativity

High IE

No d orbital

Unique ability to form pπ-pπ multiple bonds with itself and similar eles

Very high bond enthalpy as N(triple bond)N

P,As and Sb form single bond

Bi forms metallic bonds

N-N bond weaker than P-P bond due to the repulsion of non bonding e(-)s and small bond length. Hence catenation tendency is weaker in N.

Restricted covalency of 4 due to no d orbital

Cannot form dπ-dπ bonds

Front 15

Covalency?

Back 15

No. of e(-)s shared with other atoms

Front 16

Reactivity towards H 15

Back 16

Hydrides of form EH3

Stability dec from NH3 to BiH3 as bond dissociation enthalpy Dec downwards.

Reducing character inc downwards

Basicity dec downwards. SbH3>=BiH3

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Reactivity towards O2 15

Back 17

Oxides: E2O3 and E2O5

Acidic character Dec downwards

N2O3 and P2O3- purely acidic

Sb2O3 and As2O3- amphoteric

Bi2O3- basic

Front 18

Reactivity towards X 15

Back 18

Halides: EX3 and EX5

Due to no d orbital NX5 not formed

EX5 is more covalent than EX3 since in 5 the OS is of +5 due to higher (+)ve OS of central metal atom. The atoms have greater polarity effect.

3 all are stable except NX3. NF3 is stable only.

Except BiF3 all 3 are covalent

Front 19

Reactivity towards metals 15

Back 19

Form binary compounds with -3 OS

Eg. Ca3N2, Ca3P2, Na3As2, Zn3Sb2 and Mg3Bi2

Front 20

Why no NX5 ?

Back 20

No d orbital

Front 21

BP PH3< BP NH3?

Back 21

EH3 stability dec downwards as bond dissociation enthalpy Dec downwards.

And no H bonding.

Front 22

Pentahalides are more covalent then trihalides? 15

covalent then trihalides? 15

lent then trihalides? 15

Back 22

Due to higher (+)ve OS of central metal atom ie +5. The atoms have greater polarity effect.

Front 23

Prep of N2

Back 23

1. By liquefaction and fractional distillation of air. Liquid N2 distils 1st leaving liquid O2.

2. In lab:

NH4Cl(aq)+NaNO2(aq)-->N2(g)+2H2O(l)+NaCl(aq)

Impurities(HNO3 & NO) formed are removed gas thru aqH2SO4 with K2Cr2O7

3. Thermal decomp of ammonium dichromate:

(NH4)2Cr2O7(heat)--> N2(g)+2H2O(l)+NaCl(aq)

4. Very pure N2 by thermal decomp of Na/Ba azide:

Ba(N3)2-->Ba+3N2

Front 24

Pure N2 can be obtained by?

Back 24

Thermal deconp of Na/Ba azide:

Ba(N3)2--> Ba+3N2

Front 25

Prop of dinitrogen

Back 25

Colourless, odourless, tasteless and non toxic gas.

2 isotopes 14N & 15N.

Low solubility in water

Low BP and FP

Inert at room temp due to the high bond enthalpy of N triple bond N.

Reactivity inc with inc in temp

At high temp with metals gives ionic nitrides and with non metals gives covalent nitrides:

6Li/3Mg+ N2--> 2Li3N/Mg3N2

HABER'S PROCESS

At 773K with catalyst forms ammonia:

N2(g)+3H2(g) --> 2NH3(g)

Enthalpy of formation= -46.1 kJ/mol

At high temp of 2000K:

N2+O2--> NO(g)

Front 26

Manufacture of ammonia

Back 26

Haber's Process

Front 27

Uses of N2

Back 27

Manufacture of ammonia

Refrigerant

Cryosurgery

For inert atmosphere

Front 28

N2 is inert at room temperature?

Back 28

Due 2 high bond enthalpy of N triple bond N.

Front 29

Prep of ammonia

Back 29

1. In air and soil on decomp of urea:

NH2CONH2+2H2O-->(NH4)2CO3<=>2NH3+H20+CO2

2. Decomp of ammonium salts with caustic soda ( Ca(OH)2):

Photo*

3. HABER'S PROCESS

N2(g)+3H2-->2NH3(g)

Enthalpy of formation -41.6 kJ/mol

Temp~700K

Pressure of 20*10^5 Pa~200 atm atmTemp~700KCatalyst iron oxide with small amounts of K2O and Al2O3. Earlier Fe was catalyst and molybdenum was promoter.Used for large scale production of ammonia.

Catalyst iron oxide with small amounts of K2O and Al2O3. Earlier Fe was catalyst and molybdenum was promoter.Used for large scale production of ammonia.

. Earlier Fe was catalyst and molybdenum was promoter.

Used for large scale production of ammonia.

Front 30

Haber's Process?

Back 30

HABER'S PROCESS

N2(g)+3H2-->2NH3(g)Enthalpy of formation -41.6 kJ/molPressure of 20*10^5 Pa~200 atmTemp~700KCatalyst iron oxide with small amounts of K2O and Al2O3. Earlier Fe was catalyst and molybdenum was promoter.Used for large scale production of ammonia.

Front 31

Structure of NH3

Back 31

Trigonal pyramidal with N atom at the apex.

Has 3 bond pairs and 1 lone pair.

Front 32

Phy prop of ammonia

Back 32

Colorless gas with pungent smell

In solid and liquid states associated by H bonding which results in higher MP & BP than expected.

Trigonal pyramidal with N atom at the apex. Has 3 bond pairs and one lp.

Front 33

Chem prop of ammonia

Back 33

Higly soluble in water:

NH3(g)+H2O--> NH4+(aq) + OH-(aq)

Forms ammonium salts with acids such as ammonium chloride and Ammonium Sulphate.

Ammonium hydroxide is a weak base: Hence it forms Hydroxide of many metals from their salt solution:

Zns o4+nh4oh --> zn (oh)2(white solid ppt)+(nh4)2so4

Fecl3+nh4oh-->fe2o3.xh2o(brown solid ppt)+NH4Cl

Presence of lp of e(-) on N makes Ammonia a Lewis base. This property is used for detection of metal ions of Copper and silver: photo*

Front 34

Uses of ammonia

Back 34

Production of nitrogenous fertilizers

Manufacturer of inorganic nitrogen compounds like nitric acid

Liquid ammonia is used as a refrigerant

Front 35

Why does Ammonia act as a Lewis base?

Back 35

N and has one pair of electrons available for donation

Front 36

Mention the conditions required to maximise the yield of ammonia

Back 36

Temp~700KPressure of 20*10^5 Pa~200 atm atmTemp~700KCatalyst iron oxide with small amounts of K2O and Al2O3. Earlier Fe was catalyst and molybdenum was promoter.Used for large scale production of ammonia.Catalyst iron oxide with small amounts of K2O and Al2O3

Front 37

How does Ammonia react with a solution of Cu2+?

Back 37

Front 38

Oxides of nitrogen

Back 38

Front 39

Resonance structures of Nitrogen oxide

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Front 40

Why does NO2 dimerise?

Back 40

It contains odd number of Valence Electrons. It behaves as a typical odd molecule. on dimerisation it is converted to stable N2O4 with even number of electrons.

Front 41

Nitrous oxide?

Back 41

Dinitrogen oxide N2O

Front 42

Nitric oxide?

Back 42

Nitrogen monoxide NO

Front 43

Prep of Nitrous oxide and phy prop and structure

Back 43

Nh4NO3-->N2O+2H2O(heat)

Colourless gas neutral

Linear

Front 44

Prep of Nitric acid and phy prop and structure

Back 44

2Nano2+2feso4+3h2so4-->fe2(so4)3+2nahso4+2h2o+2no

Colourless gas neutral

Linear

Front 45

Prep of dinitrogen trioxide and phy prop

Nitrogen (III) oxide and structure

Back 45

2NO+N2O4-->(250K)2N203

BLUE SOLID ACIDIC

Planar

Front 46

Preparation of Nitrogen dioxide and physical properties and structure

Nitrogen (IV) oxide

Back 46

2pb(no3)2-->(673K)4no2+2pbo+O2

Brown gas acidic

Angular

Front 47

Dinitrogen tetroxide preparation and physical properties and structure

Nitrogen (IV) oxide

Back 47

2no2-->(cool)<--(heat)n2o4

Colourless solid or liquid acidic

Planar

Front 48

Dinitrogen pentoxide preparation and physical properties and structure

Nitrogen (V) oxide

Back 48

4 hn O3+P4 o10-->4 HP O3+2 n2o5

Colourless solid acidic

Planar

Front 49

Which N oxide is a blue solid?

Back 49

N2O3

Front 50

Which N oxide is a brown gas?

Back 50

NO2

Front 51

Hyponitrous acid

Back 51

H2 N2 O2

Front 52

Nitrous acid

Back 52

H No 2

Front 53

Preparation of nitric acid

Back 53

1. By heating Chile saltpetre and Indian salt battery with concentrated H2 S o4 in a glass retort:

Nano3+h2so4-->nahso4+HNO3

2. Large scale by OSTWALD'S PROCESS which is catalytic oxidation of NH3 by atmospheric oxygen:

4nh3+5o2-->(pt/Rh gauge catalyst and 500K, 9 bar) 4 NO+6h2o

2NO+O2<=>2NO2

3NO2+H2O--> 2HNO3+NO

NO formed is recycled and the aq hno3 can be concentrated by distillation of 2 68% by mass. 98% concentration can be achieved by dehydration with concentrated H2 s o4.

Front 54

Explain OSTWALD'S PROCESS

Back 54

Large scale preparation of Nitric acid by OSTWALD'S PROCESS which is catalytic oxidation of NH3 by atmospheric oxygen:4nh3+5o2-->(pt/Rh gauge catalyst and 500K, 9 bar) 4 NO+6h2o2NO+O2<=>2NO23NO2+H2O--> 2HNO3+NONO formed is recycled and the aq hno3 can be concentrated by distillation of 2 68% by mass. 98% concentration can be achieved by dehydration with concentrated H2 s o4.

Front 55

Properties of nitric acid(physical)

Back 55

Colourless liquid

Planar molecule

Strong acid

Strong oxidising agent and attacks most Noble metals

Front 56

Chemical properties of nitric acid

Back 56

Hn O3+H2O-->h3o+ + no3-

With metals:

3 CU+hn O3 dilute-->3 CU (no3)2+2 no+4 H2O

Cu+4HNO3(CONCENTRATED)-->Cu(NO3)2+2NO2+2H2O

4Zn+10HNO3(dilute)-->4Zn(NO3)2+5H2O+N2O

Zn+4HNO3(CONCENTRATED)-->Zn(NO3)2+2H2O+2NO2

Metals like Cr and Al don't dissolve in concentrated nitric acid because of the formation of a passive film of oxide on the surface.

With non metals:

I2+10HNO3-->2HIO3+10NO2+4H2O

C+4HNO3-->CO2+2H2O+4NO2

S8+48HNO3-->8H2SO4+48NO2+16H20

P4+20HNO3-->4H3PO4+20NO2+4H20

Front 57

Explain the brown ring test

Back 57

This is a test for nitrates depending on the availability of Fe2+to reduce nitrates to nitric oxide which reacts with Fe2+to form a brown coloured complex.

Aq solution containing nitrate ion is mixed with dilute ferrous sulphate solution along with a few drops of concentrated sulphuric acid.

A brown ring at the interface between the solution and Sulphuric Acid layers indicates the presence of nitrate ion in a solution.

Reaction:*photo

Front 58

Uses of nitric acid

Back 58

Manufacture of Ammonium Nitrate for fertilizers explosives and pyrotechnic.

In a preparation of nitro organic compounds

Pickling of stainless steel etching of metals and as an oxidizer in rocket fuel