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Phosphine is a chemical compound founded by Philippe Gengembre in the year 1783. This element is a part of the group of organophosphorus compounds. He obtained this compound by giving heat to phosphorous having a structural formula P4 in an aqueous solution of potassium carbonate ( K2CO3 ). The result of the chemical reaction was a colorless substance that gave a very bad odour resembling rotting fish and then it was renamed phosphine due to the bad smell. This chemical compound can be also found in tissues, blood, saliva, and other body organs too. It is one of the most vital chemical structures in learning about the elements. Phosphine's chemical formula is PH3. The concentration of phosphine keeps varying in accordance with the atmosphere. This particular portion is a part of the chapter p-block elements carrying a total weightage of 7 periods and 6 to 7 marks.
Read More About Oxoacids of Phosphorus
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Key Terms: Interhalogen Compounds, Group 15 Elements, Phosphine, atoms, chemical compound, phosphorous, heat, p-block elements
Preparation of phosphine
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Phosphine is prepared by the reaction of calcium phosphide with water ( H20 ) and dilute HCl.
Ca3P2 + 6H2O → 3Ca(OH)2 + 2PH3
Ca3P2 + 6HCl → 3CaCl2 + 2PH3
It is made in the laboratory by giving heat to white phosphorus with
concentrated NaOH sol. in an inert atmosphere of CO2(Carbon dioxide).
P4 + 3NaOH + 3H2O → PH3 + 3NaH2PO2
(sodium pyrophosphate)
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 get phosphonium iodide. Then it is treated
with KOH ( Potassium oxide ) which gives off phosphine.
PH4I KOH KI H2O PH3
Read More: Organometallic Compounds
Structure of phosphine
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The structure of phosphine looks like a pyramid. Phosphine has a structure like ammonia. The bond angle for phosphine ( H- P - H ) is 93°5. While the ammonia has a bond angle of 107°. Therefore, we can see that both ammonia and phosphine have a comparative bond angle. It is based on Levi's structure. Levis structure can also be defined as electron dot structure. The levis structure represents lone pair of electrons and the bonds with the atoms or molecules.
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Physical and chemical properties
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- They are colorless gas.
- It has an odour like a rotten fish.
- It is an incredibly poisonous gas.
- It is a dangerous and highly flammable gas.
- It has the characteristic of causing great damage to the environment.
- It is has a smell like of clove too.
- PH3 is sparingly dissolvable in water.
- Nonetheless, it can disintegrate in common or natural solvents.
- PH3 goes about as a Lewis base by parting with its solitary pair of electrons by responding with hydrogen iodide.
- Under normal conditions, it is a non-ignitable gas. If it is given the heat, then it may blast into flames providing us phosphoric acid.
- It explodes wildly when we open it to oxidizing agent.
- Other names are - PH3- phosphorus hydride, foforowodor, gas ex - B, hydrogen phosphide, etc.
Read More: Class 12 Group 15 Elements
Things to Remember
- Phosphine is a chemical compound which is part of the group of organophosphorus compounds.
- Chemical formula of Phosphine is PH₃
- Phosphine has a rotten fish odour.
- Phosphine can be found in tissues, blood, saliva, and other body organs.
- Phosphine is prepared by the reaction of calcium phosphide with water and dilutesHydrochloric acid.
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Sample Questions
Ques. What are the uses of phosphine? (2 marks)
Ans. It is an vital part of smoke screens.
- It is also used in the marine industry for giving out signals.
- Plastic industries also make use of it to create new flammable kits.
- It is used as a substance useful to form certain electrical components in semiconductor factories.
- As it has a property of spontaneous combustion it is used in Holmes signal.
- PH3 helps in killing bugs rats and rodents who are about to enter the storage of grains.
It kills them or drives them away from the place.
Ques. Explain the effects of phosphine. (3 marks)
Ans. Phosphine is a highly volatile and dangerous gas. Even if exposed a little bit, it may result in
- Dizziness
- Loose bowels
- Cough
- Cerebral pain
- Chest tightness.
If highly exposed to the gas then you might have the risk of
- Convulsions.
- Coma.
- Kidney Damage.
- Damage to the liver.
- Irregularity in a heartbeat.
Ques. Explain some of the physical properties of phosphine? (2 marks)
Ans. The chemical formula for phosphine is PH3.
- The critical temperature for phosphine is 124.9 °F.
- The Boiling Point is 126.0 °F.
- The Melting Point is 208.8 °F.
- The density of the gas for PH3 at 1 atmosphere is 0.0883.
- The molecular weight is 34.00 in ( lb/mol ).
Ques. In what way can it be proved that PH3 is basic in nature? (2 marks)
Ans. When phosphorus is reacted with acid HI to form PH4I, it will show us that
it is basic in nature.
PH3 + HI → PH4I
As there is a lone pair on the phosphorus atom, PH3
is acting as a
Lewis base in the above reaction.
Ques. How is phosphorus prepared in the laboratory? (2 marks)
Ans. It is made in the laboratory by giving heat to white phosphorus with
concentrated NaOH sol. in an inert atmosphere of CO2 ( Carbon dioxide ).
P4 + 3NaOH + 3H2O → PH3 + 3NaH2PO2
(sodium pyrophosphate)
Ques 1. Complete the following chemical reaction equation : (Delhi 2015C)
P4 + NaOH + H2O
Ans. P4 + NaOH + H2O → PH3 + 3NaH2PO2
Ques 2. Complete the following chemical equations : (Delhi 2014)
Ca3P2 + H2O
Ans. Ca3P2 + H2O → 3Ca(OH)2 + 2PH3
Ques 3. Complete the following equation : (AI 2011)
HgCl2 + PH3
Ans. HgCl2 + PH3 → Hg3P2 + 6HCl
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