P Block Flashcards
What are apatites
Minerals of phosphorus.. they occur in rocks..
Ex- ** Ca10(PO4)6X2 **
Here X - F , Cl , OH.. iske alava nhi ho skta koi aur
Discuss Ionisation energy 1 for group 15
Very high Ionisation energy
Brief about the physical state of group 15
Nitrogen exists as gas coz pπ-pπ bond
Rest cannot form pπ-pπ bonds hence exist as tetramers
Discuss about hydrides of group 15
Thermal stability.. Lewis base strength… And bond angle decreases down the group.
Reducing power and size of hydrides increases down the group
Give order for mp and bp of group 15 hydrides
MP— PH3 < AsH3 < SbH3 < NH3
BP—- PH3 < AsH3 < NH3 < SbH3 < BiH3
Give stability of +3 +5 and -3 oxidation state of group 15 elements
Stability of -3 and +5 decreases down the group…while +3 ki stability increases down the group due to inert pair effect
Wat is inert pair effect
Poor shielding of f and d causes inner electrons to be tightly bound to nucleus and hence low oxidation becomes more stable
Types of halides of group 15
Does Nitrogen form both the halides?
MX3 and MX5…
MX5 is more covalent than MX3
nitrogen does not form MX5 coz no vacant d orbital..
Which oxide of nitrogen is k/a the laughing gas
Dinitrogen oxide.. nitrous oxide.. ( N2O)
NEUTRAL OXIDE
Explain about the sesquioxide of nitrogen
N2O3
acidic oxide
Blue solid
Anhydride of HNO2 (nitrous acid)
Give important points of Nitrogen dioxide
NO2.. reddish brown gas.. acidic oxide
Mixed anhydride of HNO2 and HNO3.
odd electron molecule and paramagnetic.
Nitrogen dioxide at low temperature dimerises to form N2O4 (dinitrogen tetraoxide) which is colourless acidic and diamagnetic oxide
Which is the most stable allotrope of phosphorus? And how is it formed?
Black phosphorus
Red p -803k—– alpha black phosphorus
White P —-473k and high pressure —— beta black phosphorus (polymeric )
Which is the most reactive allotrope of phosphorus
White phosphorus.. catches fire in air hence stored under water.
Molecular solid.
Chemiluminiscence
Poisonous
Soluble in CS2.. not soluble in water
Most reactive due to angle strain(60°)
Wat describes the basicity of oxoacids?
Basicity of oxoacids is due to O-H bonds
How would you know that an oxoacid is a strong reducing agent
By seeing the number / presence of P-H BONDS
Hypophosphorous VS hypophosphoric
Hypophosphorous - H3PO2 (phosphinic acid)
Monobasic.. strong reducing agent..
Hypophosphoric — H4P2O6
has P-P bond.
Not a reducing agent
ORTHOPHOSPHOROUS
VS
ORTHOPHOSPHORIC
ORTHOPHOSPHOROUS
H3PO3
**phosphonic acid **
Dibasic and reducing agent
ORTHOPHOSPHORIC
H3PO4
tribasic acid (paani mein 3 h+ dega)
PYROPHOSPHOROUS
VS
PYROPHOSPHORIC
PYROPHOSPHOROUS
H4P2O5
has p-o-p bond
PYROPHOSPHORIC
**H4P2O7 **
Has p-o-p bond
Difference between PHOSPHORUS and PHOSPHORIC
Structure bnao.. PHOSPHORIC mein saare OH and ek double bond o..
And PHOSPHOROUS mein el double bond o and 2 OH and ek PH
Metaphosphoric acid ke two forms?( HPO3)
1) cyclotrimetaphosphoric acid
(HPO3)3= H3P3O9
P-O-P BOND in cyclic ring..
2)polymetaphosphoric acid
P-O-P bond.
How to prepare pure Nitrogen
By thermal decomposition of azides (N3- ions)
Write reaction for ammonium dichromate ka thermal decomposition to prepare nitrogen
(NH4)2Cr2O7——– N2 + Cr2O3 + H20
Ammonium dichromate is a very powerful oxidising agent
Test for NH3
Using nessler’s reagent
K2[HgI4]
Nh3 with nessler’s reagent and a base forms .. ** iodide of millons base** which is a brown ppt
H2N-Hg-O-Hg-I
Prepration of nessler’s reagent
HgCL2+2Ki—-Hgi2 +2KCL
! (Excess KI)
!
K2[HgI4]
For wat is OSTWALD process used?
For industrial preparation of HNO3 (NITRIC ACID) OSTWALD process is used.
Step 1- oxidation of NH3 — NO..
Step 2- oxidation of NO— NO2
Step 3 hydrolysis of
NO2— HNO3 + NO
Test for NO3- ions
Brown ring test
[Fe(H2O)5(NO)]SO4
Os of fe—- +1
Os of No—- +1 (yhaan NO neutral nhi coz voh apna ek e- fe ko dekar use +1 mein laata)
Properties of phosphine gas (PH3)
Colourless
Highly poisonous
Rotten fish smell
Very less soluble in water
Explodes in contact with oxidising agents like HNO3 CL2
Aq Solution of ph3 decomposes in light to give red p and h2
It is a weak lewis base
Pure phosphine is non- inflammable but becomes inflammable due to impurities of P2H4(diphosphane) and P4 vapours
Thionyl chloride is used in preparation of?
Thionyl chloride - SOCL2
Used in preparation of phosphorus trichloride
Sulphuryl chloride is used in preparation of?
Sulphuryl chloride - SO2CL2 is used in preparation of phosphorus pentachloride
Wat is POCL3
Phosphoryl chloride. On reaction with water it gives H3PO4 and HCl
PCL5 WITH excess water reaction and PCL5 WITH less water reaction
Excess water-(more water)
Product - H3PO4 (ORTHOPHOSPHORIC acid) and hcl
Less water-
Product - POCL3 (phosphoryl chloride) and hcl
Can PCL5 act as an reducing agent?
NO. PCL5 can only act as in oxidising agent coz ye already+5 mein hai
Order of electron gain enthalpy for group 16
S> Se> Te> Po> O
( Oxygen ki least)
(Sulphur ki maxm) (-ve)
Comment on stability of os— +4 and +6
Stability of +6 decreases down the group..
Stability of +4 increases down the group
Order of mp and bp of hydrides of group 16
H2S < H2Se< H2Te< H2O
Hydrides of 16 behave same as 15
Acidic strength increases down the group
Comment on the existence of SO3 in gaseous and solid state
In gaseous state -
Sp2 planar.. resonance hybrid
In solid state.. sp3 cyclic trimer
Puckered ring structure is seen in which allotrope of sulphur
Yellow rhombic sulphur (angle- 108°) aka alpha sulphur
Most stable form at room temperature
S8 molecular solid
Insoluble in water
Wat is transition temperature
At 369k both beta and alpha form of sulphur are stable and this temp os called transition temperature
Does sulphur exist at very high temperature like 1000k??
Yes.. as S2 molecule which is PARAMAGNETIC due to unpaired π° amo (like O2)
Gove similarities in the 7 oxoacids of sulphur
All are dibasic
Sulphur in all is sp3 hybridised
Wat is peroxomonosulphuric acid
Caro’s acid
H2SO5
Wat is peroxodisulphuric acid
Aka MARSHALL’S ACID
H2S2O8
Is ozone thermodynamically unstable ?
Yes.. Ozone is thermodynamically unstable than oxygen.. so high conc of ozone can be dangerously explosive
Properties of ozone
Violet black solid
Dark blue liquid
Pale blue gas
Diamagnetic
V powerful oxidising agent and bleaching agent
Wat is iodometry and tailing of mercury
Iodometry - quantitative estimation of ozone (indicator- starch)
Qualitative estimation of ozone is called tailing of mercury
Talk about reducing power and bleaching action of sulphur dioxide
V strong reducing agent in acidic medium
Bleaching action is temporary due to evolution of nascent hydrogen
Wat is frasch process
Used to extract the underground deposits of sulphur
Oxidising powers of hno3. H2so4 and H3PO4
Hno3> h2so4
H3PO4 is non oxidising
Nitrogen shows allotropy in
Solid state
In the compound NCL3 negative oxidation state is shown by
Nitrogen coz it’s more EN
