Chemical Properties of Phosphine and Introduction to Organic Chemistry

Vocabulary practice flashcards covering the chemical properties, preparation methods, reactions, and uses of phosphine, along with fundamental concepts, history, and comparison of organic and inorganic compounds.

Basic Nature of Phosphine ($PH_3$)

Phosphine is basic in nature, but less basic than ammonia ($NH_3$). It reacts with water to form phosphonium hydroxide ($PH_4OH$) and hydroxide ions ($OH^-$).

Phosphonium Salt Formation

The reaction of phosphine ($PH_3$) with acids to form phosphonium salts, such as $PH_3 + HCl \rightarrow PH_4Cl$ (Phosphonium chloride) and $PH_3 + HBr \rightarrow PH_4Br$ (Phosphonium bromide).

Preparation of Phosphine from Calcium Phosphide

Phosphine gas is prepared by reacting calcium phosphide with water: $Ca_3P_2 + 6H_2O \rightarrow 3Ca(OH)_2 + 2PH_3\uparrow$

Preparation of Phosphine from Phosphonium Iodide

Phosphine gas is obtained by reacting phosphonium iodide with potassium hydroxide: $PH_4I + KOH \rightarrow PH_3\uparrow + KI + H_2O$

Preparation of Phosphine from White Phosphorus

Phosphine gas is obtained by heating white phosphorus with sodium hydroxide and water: $P_4 + 3NaOH + 3H_2O \rightarrow PH_3\uparrow + 3NaH_2PO_2$

Reducing Property of Phosphine ($PH_3$)

Phosphine acts as a powerful reducing agent that reduces heavy metal salt solutions into metallic phosphides or oxides, which subsequently decompose into corresponding pure metals upon standing or heating.

Reaction of Phosphine with Copper Sulfate ($CuSO_4$)

When $PH_3$ is passed through a $CuSO_4$ solution, it reduces $CuSO_4$ to a black precipitate of cupric phosphide ($Cu_3P_2$), which decomposes on heating into copper metal: $4PH_3 + 6CuSO_4 \rightarrow 2Cu_3P_2 + 6H_2SO_4$ and $2Cu_3P_2 \rightarrow 6Cu + P_4$

Reaction of Phosphine with Silver Nitrate ($AgNO_3$)

When $PH_3$ is passed through an $AgNO_3$ solution, it reduces $AgNO_3$ into a black precipitate of silver phosphide ($Ag_3P$), which decomposes on standing into silver metal: $PH_3 + 3AgNO_3 \rightarrow Ag_3P\downarrow + 3HNO_3$ and $4Ag_3P \rightarrow 12Ag + P_4$

Reaction of Phosphine with Oxygen

Phosphine reacts with oxygen to form phosphoric acid ($H_3PO_4$) in limited oxygen ($PH_3 + 2O_2 \rightarrow H_3PO_4$) or phosphorus pentoxide ($P_2O_5$) in excess oxygen.

Reaction of Phosphine with Chlorine

Phosphine reacts with chlorine to produce phosphorus trichloride ($PH_3 + 3Cl_2 \rightarrow PCl_3 + 3HCl$) or phosphorus pentachloride ($PH_3 + 4Cl_2 \rightarrow PCl_5 + 3HCl$), depending on the amount of chlorine used.

Holmes Signal

A signal provided to ships using containers of calcium carbide ($CaC_2$) and calcium phosphide ($Ca_3P_2$), which react with water to release acetylene ($C_2H_2$) and phosphine ($PH_3$), producing a bright flame and smoke.

Smoke Screen Use of Phosphine

Phosphine ($PH_3$) is used to create smoke screens in war due to its poisonous property.

Organic Chemistry (Modern Definition)

The branch of chemistry that deals with the study of hydrocarbons and their derivatives.

Organic Compounds

Hydrocarbons and their derivatives containing covalently bonded carbon atoms as an essential element, such as methanol ($CH_3OH$), chloroform ($CHCl_3$), ethene ($CH_2=CH_2$), and vinyl chloride ($CH_2=CH-Cl$).

Vital Force Theory

A historical theory stating that organic compounds are formed only by living organisms (plants and animals) under the influence of a vital force and cannot be synthesized in the laboratory.

Wohler Synthesis of Urea

In $1928$, German scientist Fedrick Wohler accidentally synthesized organic urea ($NH_2CONH_2$) by heating inorganic ammonium sulphate and potassium cyanate: $(NH_4)_2SO_4 + 2KCNO \rightarrow 2NH_4CNO + K_2SO_4$, followed by molecular rearrangement $NH_4CNO \rightarrow NH_2CONH_2$.

Catenation in Organic Chemistry

The property of carbon forming covalent bonds with other carbon atoms, leading to over $10\text{ million}$ organic compounds compared to around $1\text{ million}$ inorganic compounds.

Functional Group

A structural feature present only in organic compounds that determines their chemical functions and reactivity.

Isomerism

A phenomenon present in organic compounds where different compounds share the same molecular formula; it is absent in inorganic compounds.

Solubility Comparison of Organic and Inorganic Compounds

Organic compounds are generally insoluble in water, whereas inorganic compounds are water-soluble.

Combustibility Comparison of Organic and Inorganic Compounds

Organic compounds are highly inflammable due to their covalent nature, whereas inorganic compounds are not as highly inflammable.