Question
Write a note on the following :
(1) Rhombic sulphur
(2) Monoclinic sulphur
(1) Rhombic sulphur
(2) Monoclinic sulphur
✓
Answer
(1) Rhombic sulphur :
(2) Monoclinic sulphur :
- Rhombic sulphur are orthorhombic crystals.
- This is the most stable form and common form of sulphur.
- It is pale yellow., having density $2.069 g / cm ^3$ and melting point $385.8 K$
- It is insoluble in water, but soluble in $CS _2$
- It is stable below 369 K and transforms to β-sulphur above this temperature.
- It exists as $S _8$ molecules with a structure of a puckered ring.
- It is obtained by the evaporation of roll sulphur is $CS _2$.
(2) Monoclinic sulphur :
- Monoclinic sulphur ($\beta$ sulphur or prismatic sulphur) are needle-shaped monoclinic crystals.
- It is bright yellow, having a density $1.989 gcm ^3$ and melting point 393 K.
- It is soluble in $CS _2$.
- It is stable above 369 K and transforms into α-sulphur below this temperature.
- It exists as, $S _8$ molecules with a structure of a puckered ring.
- It is prepared by melting rhombic sulphur and cooling it till a crust is formed. Two holes are pierced in the crust and the remaining liquid is poured to obtain needle-shaped crystals of monoclinic sulphur.
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