P Block 8 Flashcards
NH3(excess) with Cl2 forms
heating Pb (NO3)2 forms
Cl2 with Hot conc NaOH forms
Conc HNO3 with I2
In the earth’s crust, it occurs as sodium nitrate, NaNO3
(called Chile
saltpetre) and potassium nitrate (Indian saltpetre).
Ca9 (PO4
)6
. CaF2
) which are the main components of phosphate rocks
Arsenic, antimony and bismuth are found mainly as
sulphide minerals
The only well characterised
Bi (V) compound is BiF5
.
3HNO2 → HNO3
+ H2O + 2NO
N–N bond is weaker than the single P–P bond because of high
interelectronic repulsion of the non-bonding electrons, owing to the
small bond length
As a result the catenation tendency is weaker in nitrogen.
BiH3 is the
strongest reducing agent amongst all the hydrides
Their acidic character decreases down the group.
In case of nitrogen, only NF3 is known to be stable.
State will have more polarsing power than in +3 oxidation state. the covalent character of bonds is more in pentahalides.
synthetic radioactive element
Due to high electronegativity and small size of nitrogen
NH3 exhibits hydrogen bonding in solid as well as liquid state.
these impurities can be removed by passing the gas through aqueous
sulphuric acid containing potassium dichromate
high pressure would
favour the formation of ammonia
Earlier, iron was used as a catalyst with
molybdenum as a promoter
In the laboratory, nitric acid is prepared by heating KNO3
or NaNO3
and concentrated H2SO4
in a glass retort.
On a large scale it is prepared mainly by Ostwald’s process.
NO thus formed is recycled and the aqueous HNO3
can be
concentrated by distillation upto ~ 68% by mass. Further
concentration to 98% can be achieved by dehydration with
concentrated H2SO4
Concentrated nitric acid is a strong oxidising agent and attacks
most metals except noble metals such as gold and platinum.
adding dilute ferrous sulphate solution to an aqueous solution
containing nitrate ion, and then carefully adding concentrated sulphuric
acid along the sides of the test tube. A brown ring at the interface
between the solution and sulphuric acid layers indicates the presence
of nitrate ion in solution.
A brown ring at the interface
between the solution and sulphuric acid layers indicates the presence
of nitrate ion in solution.
more reactive than
the other solid phases under normal conditions because of angular
strain in the P4
molecule where the angles are only 60°
It readily
catches fire in air to give dense white fumes of P4O10.
Red phosphorus possesses iron grey lustre
In the laboratory, it is prepared by heating white phosphorus with
concentrated NaOH solution in an inert atmosphere of CO2
.
When pure, it is non inflammable but becomes inflammable owing
to the presence of P2H4 or P4 vapours
When pure, it is non inflammable but becomes inflammable owing
to the presence of P2H4 or P4 vapours
To purify it from the impurities it is absorbed in HI to form phosphonium iodide (PH4I) which on treating
with KOH gives off phosphine.
PH4I + KOH—> KI+ H2O+ PH3
The solution of PH3 in water decomposes
in presence of light giving red phosphorus and H2.
Phosphine is weakly basic and like ammonia, gives phosphonium
compounds with acids e.g.,
Thionyl chloride with white phosphorus.
P4+ 8SOCl2–> 4PCl2+ 4SO2 +2S2Cl
It reacts with organic compounds containing –OH group such as
CH3COOH, C2H5OH.
It reacts with organic compounds containing –OH group converting
them to chloro derivatives.
C2H5 OH + PCl5–> C2H5Cl+ POCl3+ HCl
CH3COOH+ PCl5–> CH3COCl+ POCl3 +HCl
two axial bonds are longer than equatorial bonds.
This is due to the fact that
the axial bond pairs suffer more repulsion as compared
to equatorial bond pairs
These acids in +3 oxidation
state of phosphorus tend to disproportionate to higher and lower
oxidation states.
These P–H bonds are not ionisable to give H+
and do not play any
role in basicity. Only those H atoms which are attached with oxygen in
P–OH form are ionisable and cause the basicity.
Thus, H3PO3 and H3PO4 are dibasic and tribasic, respectively as the structure of H3PO3
has two P–OH bonds and H3PO4 three.
forms about 46.6% by mass of earth’s crust. Dry air contains 20.946%
oxygen by volume.
Traces of sulphur occur as hydrogen sulphide in volcanoes. Organic
materials such as eggs, proteins, garlic, onion, mustard, hair and wool
contain sulphur.
Polonium occurs in nature as a decay
product of thorium and uranium minerals.
Because of the compact nature of oxygen atom, it has less negative
electron gain enthalpy than sulphur
increase in acidic character can be explained
in terms of decrease in bond enthalpy for the dissociation of H–E
bond down the group.
Owing to the decrease in enthalpy for the
dissociation of H–E bond down the group, the thermal stability of
hydrides also decreases from H2O to H2Po.
The stability of the halides
decreases in the order F– > Cl– > Br– > I–
.
The well known monohalides are dimeric in nature.
Examples are S2F2+, S2Cl2, S2Br2, Se2Cl2 and Se2Br2
These dimeric halides undergo
disproportionation as given below
2Se2Cl2 → SeCl4 + 3Se