JEE Mains National Test Abhiyas Official Questions Chemistry Part 48- Flexiprep

9/22/2021 JEE Mains National Test Abhiyas Official Questions Chemistry Part 48- FlexiPrep

FlexiPrep JEE Mains National Test Abhiyas Official Questions Chemistry Part 48 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q. 20 Which of the following is a cyclic oxyacid?

Answer: C

Explanation:

is a cyclic trimetaphosphoric acid.

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Key Concepts Examples on Oxyacid՚s of phosphorus

Oxyacid՚s of phosphorus: Phosphorus forms a few oxyacid՚s which differs in their structure and oxidation state of phosphorus. These are

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are reducing agents. (Pyrophosphoric acid) is dibasic acid. is formed by dehydration of at .

Oxidation state of and Name Structure Basicity

, Hypophosphorous acid Monobasic

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, Phosphorus acid Dibasic

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, Hypophosphoric acid Tetrabasic

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, Orthophosphoric acid Tribasic

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Metaphosphoric acid ,

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Monobasic

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, Pyrophosphoric acid (Diphosphoric acid) Tetrabasic

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Oxyacid՚s of Phosphorus

Compounds of Phosphorus Ill. Oxides and oxyacids of phosphorus: Phosphorus is quite reactive and forms number of compounds in oxidation states of and . Phosphorus forms two common oxides namely,

Phosphorus trioxide and

phosphorus pentaoxide .

a. Phosphorus (III) oxide :

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It is formed when is burnt in a limited supply of air,

(limited)

It is a crystalline solid with garlic odor. It dissolves in cold water to give phosphorous acid,

Cold Phosphorus acid

It is therefore, considered as anhydride of phosphorus acid. With hot water, it gives phosphoric acid and inflammable phosphine,

Hot Phosphorus acid

It reacts vigorously with to form a mixture of phosphoryl chloride and metaphosphoryl chloride

b. Phosphorus (V) oxide :

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It is prepared by heating white phosphorus more than air.

(Excess)

It is snowy white solid. It readily dissolves in cold water forming Metaphosphoric acid.

Cold Metaphosphoric acid

With hot water, it gives phosphoric acid,

Heat Phosphorus acid

is a very strong dehydrating agent. It extracts water from many compounds including and .

;

Oxyacids of Nitrogen Oxyacids of nitrogen: Oxyacids of nitrogen are (Nitroxylic acid) and (Pemitric acid) , which are explosive.

i. Nitrous acid : It is prepared by adding ice cold dil. or dil. to a well cooled solution of any nitrite ( , etc.) .

It oxidizes to to and acts as a reducing agent in presence of strong oxidizing agent, i.e.. , it reduces acidified etc. to and respectively.

ii. Nitric acid : is called aqua Fortis. It is prepared in the laboratory by distillation of nitrite with conc.

Commercially, it is obtained by Ostwald՚s process. In this process, NH3 is first catalytically oxidized to which is cooled to about and then oxidised by air to . Absorption of in water in presence of oxygen gives

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From air (Birkrland Eyde electric arc process)

Properties It is a very strong acid and decomposes on boiling or in presence of sunlight. It acts as a strong oxidizing agent. It oxidizes non-metals and metalloids to their respective oxy-acids, i.e.. , (to , to , to , to , to ) (arsenic acid) and to (Antimonic acid) , while nitric acid itself is reduced to .

Nitric acid reacts with metals to form nitrates and is itself reduced to or (which further reacts with to give ) depending upon the concentration of the acid, activity of the metal and the temperature of the reaction.

iii. Very active metals such as etc. give on treatment with very dilute .

iv. Less active metals like etc. give with dil. . Zinc, however, gives with dil.

and NH4N with very dilute .

Similarly, and react with dilute nitric acid to give .

i. Conc. gives both with active metals ( etc) and less active metals ( etc.)

ii.

Tin is, however, oxidized by conc. to metastannic acid .

Passivity and become passive in conc. (i.e.. , lose their normal reactivity) due to the formation of a thin protective layer of the oxide on the surface of the metal which prevents further action. Nitric acid has no action on noble metals but these metals dissolve in aqua regia forming their respective chlorides.

These chlorides subsequently dissolve more than forming their corresponding soluble complexes. Thus,

Auric chloride Aurochloric acid

Platimic chloride Chloro Platimic acid

Sugar on oxidation with nitric acid gives oxalic acid. Nitric acid reacts with glycerine to give glycerol trinitrate or nitro glycerine, with toluene it gives 2,4, 6-trinitrotoluene (T. N. T.) and with cellulose (cotton) it gives

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cellulose trinitrate (gun cotton) . All these are used as explosives.

Oxidation Name of Molecular state Structure Basically Nature oxyacid formula of

Hyponitrous Very Highly 2 (Dibasic) acid weak explosive

1 Unstable Nitrous acid weak (Monobasic) acid

1 Stable Nitric acid strong (Monobasic) acid

1 Unstable Pernitric and acid (Monobasic) explosive

All These Are Used as Explosives

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