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Wednesday, July 3, 2019

NITROGEN : AND ITS PROPERTIES:


Nitrogen (N) and its Behaviour:
(1) Nitrogen is the lightest element of 15th group with the symbol N and atomic number 7. It often called the pnictogens. The name pnictogens comes from the Greek πνίγειν "to choke", directly referencing nitrogen's asphyxiating properties.
(2) The name Nitrogen gets its name from a mineral known as “niter” (potassium nitrate), from which it can be prepared. It was first discovered and isolated by a Scottish physician Daniel Rutherford in 1770.
(3) Nitrogen is a fairly common element in the earth’s crust. It is most important constituent of atmosphere, making up to 78.08 %. Nitrogen is a colorless, odorless, non combustible and nontoxic gas. Makes up the major portion of the atmosphere, but will not support life by itself.
(4) The greatest use of nitrogen is in ammonia which is used for fertilizer production and to produce nitric acid. Nitrogen gas is used where inert atmosphere is needed, such as in an ordinary light bulb. Nitrogen is also used in protecting historic documents. Nitrogen is also used in storage of food stuff and in explosives.
(5) Nitrogen is use in purging air conditioning and refrigeration systems, and in pressurizing aircraft tires. It May cause asphyxiation by displacement of air. Under prolonged exposure to fire or heat containers may rupture violently and rocket
(6) Nitrogen is absolutely essential to all living organisms. It is important part of all protein molecules which, among other functions, are the building materials in all kinds of cells.

Abnormal Behaviour of Nitrogen:

(1) Nitrogen is a gas, while other elements are solids.
(2) Nitrogen molecule is diatomic (N2) while molecules of P, As and Sb are tetra atomic (P4, As4, Sb4) and that of Bi is mono atomic.
(3) Halides of nitrogen except NF3 are highly explosive.
(4) N2O3 and N2O5 are monomeric while trioxides and pentoxides of P,As and Sb are dimeric.
(5) It is chemically inert due to the presence of triple bond other elements are highly reactive due to presence of single bond in their molecule.
(6) N2, CO, (CN)¯ are isoelectronic species but N2 is less reactive due to nonpolar nature and high ionisation energy.
(7) N does not form sulphides.

Related Questions:



Trisilyl amine, N(SiH3)3 is planar whereas trimethyl amines N(CH3)3 is pyramidal. Explain why?.















Tuesday, July 2, 2019

Oxy acids of Phosphorous:


Phosphorus forms two series of oxyacids namely; phosphorus acid and phosphoric acid.
SN
Element
Formula
Name of the Oxyacid
O.S.
2
Phosphorus
H3PO2
H3PO3
H4P2O7
Hypo Phosphorus acid
Ortho Phosphorus acid
Pyro phosphorous acid
+1
+3
+3
3
Phosphoric
H4P2O6
H3PO4
 H4P2O7
(HPO4)n
Hypo Phosphoric acid
Ortho Phosphoric acid
Pyro Phosphoric acid
Meta phosphoric acid
+4
+5
+5
+5
4
Arsenic
H3AsO3
H3AsO4
Arsenious acid
Arsenic acid
+3
+5
5
Sb & Bi
No stable acid



 (A) Phosphorus acid series: (Structure)
The series consists of p atom exhibiting oxidation state of +3. They act as reducing agents.
                

(B) Phosphoric acid series: (Structure) 
This series consist of acids having p in +5 oxidation state.
   
                           
Note : Meta phosphoric does not exist in monomeric form, but it exists as cyclo meta phosphoric acid (HPO3)3 or   polymeta phosphoric acid (HPO3)n.  Sodiumhexametaphosphate is a famous salt known as CALGON  and use water softener.


Special Note:
(1)  Meta is used for acid obtained by loss of H2O molecule.
(2)  Pyro is used for the acid obtained from two molecules with a loss of H2O.
(3)  Hypo is used for the acid having lower oxygen content than the parent acid.

Related Questions:



Trisilyl amine, N(SiH3)3 is planar whereas trimethyl amines N(CH3)3 is pyramidal. Explain why?.















Oxyacids of Nitrogen :



S.N.
Formula
Name of acids
Oxidation No. of N

1
H2N2O2 or HNO
Hyponitrous acid
+1
2
H4N2O4 or H2NO2
Hydroxynitrous acid
+2
3
HONO or HNO2
Nitrous acid
+3
4
HOONO
Pernitrous acid
+4
5
HNO3
Nitric acid
+5
6
HNO4
Pernitric acid
+6
 (1) Hyponitrous acid (H2N2O2):
 Hyponitrous acid is a chemical compound with formula H2N2O2 or HON=NOH. Hyponitrous acid is a weak acid in aqueous solution and decomposes to N2O and water. It is an isomer of nitramide [H2N−NO2].
Hyponitrous acid forms two series of salts, the hyponitrites containing the [ON=NO]2− anion, and the "acid hyponitrites" containing the [HON=NO]anion.
           

(2) Nitrous acid (HNO2):
Nitrous acid (HNO2) is a weak and monobasic acid known only in solution and in the form of nitrite (NO2) salts. Nitrous acid is used to make diazonium salts from amines. The resulting diazonium salts are reagents in azo coupling reactions to give azo dyes.
      

(3) Nitric acid (HNO3):
Nitric acid is also known as aqua fortis (meaning strong water) which was given by alchemists.
 
Related Questions:



Trisilyl amine, N(SiH3)3 is planar whereas trimethyl amines N(CH3)3 is pyramidal. Explain why?.