Question

Which allotrope of phosphorus has a higher density?

Answer 1

Allotropes

• Allotropes are two or more forms of the same elements that exist in the same physical state (solid, liquid, or gas) but have physical and chemical properties that differ from one another.
• Most allotropes of phosphorus are white, red, and black.
• White phosphorus is less stable due to angular strain in the ${\text{P}}_{\text{4}}$molecule where the angles are only ${60}^{°}$.
• Black phosphorus has two forms α-black phosphorus and β-black phosphorus.
• α-Black phosphorus is formed when red phosphorus is heated in a sealed tube at $803\text{K}$.
• Red phosphorus is obtained by heating white phosphorus at $573\text{K}$ in an inert atmosphere for several days.

Order of density

• The order of density of allotropes of phosphorus is as follows:-
• Black phosphorus>Red phosphorus>White phosphorus
• The tendency of polymerization increases and the compactness of the substance also increases in the given allotropes.

So, the black phosphorus has a higher density.