Sulphur and its Allotropic Forms

Introduction

Sulphur naturally occurs near volcanoes and massive deposits in Texas and Louisiana in the USA. Sulphur helps in preparing batteries, detergents, and fungicides, manufacture of fertilizers, gunpowder, matches and fireworks. In chemical and pharmaceutical industries, the chemical compound is used to make stronger and first resistant concrete materials.

What is Sulphur?

Sulphur in nature is present as sulphides and has several vital ores such as chalcopyrite, bornite, pentlandite, millerite and molybdenite. Sulphide minerals that are formed from sulphur include pyrite and marcasite are iron sulphide, and stibnite is antimony sulphide.

Figure 1 − Allotropic forms of Sulphur

The other major minerals of sulphur include galena is lead sulphide, cinnabar is mercury sulphide, and sphalerite is zinc sulphide. Sulphuric acid $\mathrm{(H_{2}SO_{4})}$ is the main derivative of Sulphur that is used to manufacture corrosion-resistant concrete.

Properties of Sulphur

The reaction of sulphur with other compounds can be determined after evaluating the phenomenon that most of non-metals and metals highly react with sulphur. Hydrogen sulphide is obtained when sulphur reacts with hydrogen at a high temperature. Sulphur burns at a higher rate of air with a bright blue fire, and generally produces Sulphur (IV) oxide and a little amount of Sulphur (VI) oxide. The chemical and physical properties of Sulphur are listed below.

Properties of Sulphur
Electro negativity	2.5
according to Pauling
Atomic mass	32.06 g.mol-1
Atomic number	16
Boiling point	445°C
Density	2.07 g.cm-3 (20°C)
Melting point	113°C
Vanderwaal's radius	0.127 nm
Ionic radius	0.184 (-2) nm; 0.029 (+6)
Isotopes	5
Standard potential	- 0.51 V
Electronic shell	$\mathrm{[Ne]3S^{2}3p^{4}}$
Energy of Ionization	1st: 999.3 kJ.mol-1; 2nd: 2252 kJ.mol-1; 3rd: 3357 kJ.mol-1.
Reactions	Sulphur reacts with the majority of non- metals and metals, like hydrogen to produce hydrogen sulphide. Sulphur vapour generally reacts with hot coke to form a fluid, and carbon disulphide.

Table 1: Properties of Sulphur

Allotropic forms of Sulphur

Sulphur is highly used in the formation of phosphoric acid, which helps in the production of organic manure. Sulphur is a naturally formed chemical compound that usually forms near volcanoes and forms several allotropes as discussed below:

Rhombic sulphur (α-sulphur)

Rhombic sulphur has a yellow crystalline appearance with an octahedral shape. The solution of roll sulphur is heated in CS2 in order to derive rhombic sulphur. This yellow compound has a melting point of 385.8K and an exact gravity of 2.06. This allotropic form of Sulphur has a lower solubility rate in water but get dissolves easily in benzene, ether, alcohol and so on.

Figure 2 − Rhombic sulphur (α-sulphur)

Monoclinic sulphur (β-sulphur)

Monoclinic sulphur can be obtained by melting the yellow rhombic sulphur (α-sulphur) and cooling it. In the crust, 2 holes are made and the liquid is poured into it to get clear and needle-shaped crystals of β-sulphur after removal.

Applications of Sulphur

Some common uses or applications of Sulphur are mentioned below.

• Sulphur is widely utilised for vulcanize black rubber as an effective fungicide and in the formation of black gunpowder.

• The compound can also be used to prepare sulphuric acid, which is the very essential chemical prepared by western civilisations.

• Sulphur is highly used in the formation of phosphoric acid, which helps in the production of organic manure.

• The chemical compound can also be used in the creation of several materials including pesticides, herbicides, and silver polish.

• The product of sulphur, the Sulphuric acid $\mathrm{H_{2}SO_{4}}$ is the major component that is widely utilized as an industrial raw material and a derivative of sulphur.

• Sulphur is incorporated in the production of batteries, detergents, fungicides, fertiliser production, insecticides, gun powder, matches, and fireworks.

• The compound is very effective in the preparation of several corrosive concrete that have higher strength and frost resistance. The concretes include solvents, medicinal and petrochemical products.

Effects of Sulphur

Sulphur is referred to as a multivalent, abundant, tasteless and odourless non-metal that has a yellow crystalline solid appearance. Excessive exposure to Sulphur has some severe impacts on the health of humans on a global scale as stated below.

• Abnormalities in Blood circulation

• Loss of reproduction ability

• Severe damage to heart and lungs

• Neurological impacts and behaviour alterations

• Defects in hearing, and vision

• Impairment of immune system

• Irritable bowel syndrome and other gastrointestinal issues

• Reduce the function of liver and kidneys

• Effects on skin and hormonal metabolism

Conclusion

Sulphur can be used in preparation of carbon disulphide that is generally included in skin ointments and skin moisturizers. Sulphur has a high rate of utility in industries and plays an essential role in the ecosystem as it helps in the growth and development of plants. The two major allomorphic forms of Sulphur are yellow rhombic sulphur (α-sulphur) and the monoclinic (β-sulphur).

FAQs

1. What are the major features of Sulphur?

The most vital feature of Sulphur is its thermal stability and its allotropes are determined as inter-convertible. In this case, yellow rhombic sulphur (α-sulphur) produces monoclinic sulphur at 369K or above.

2. What are the chemical properties of Sulphur?

The majority of non-metals and metals highly react with sulphur. Hydrogen sulphide is obtained when sulphur reacts with hydrogen at a high temperature. Sulphur burns at a higher rate of air with a bright blue fire, and generally produces Sulphur (IV) oxide and a little amount of Sulphur (VI) oxide.

3. What are the major types of sulphur?

Sulphur is referred to as a multivalent, abundant, tasteless and odourless non-metal that naturally occurs near volcanoes. The major allotropic forms or types of sulphur include Rhombic sulphur (α-sulphur), Monoclinic Sulphur (β-sulphur), Colloidal Sulphur, and Milk of Sulphur.