Sulfur (S), as it is known in the Periodic Table of Elements, is a tasteless and odorless yellow nonmetallic compound belonging to the oxygen group.

It exists as solid, insoluble in water, and a poor conductor of electricity.

Sulfur reacts with several elements to form sulfides, and its main industrial use is making sulfuric acid.

The element’s atomic number is 16, and its atomic weight is 32. Sulfur is neither a compound nor a mixture but a pure element. So, what makes sulfur a pure substance, not a mixture?

Why is sulfur a pure substance?

Pure substances are made of only one kind of particle and have a fixed chemical nature. In fact, pure substances can be elements or compounds since some compounds contain one type of atom. Some characteristics and properties of pure substances include:

  • They contain one type of atoms or molecules
  • They have fixed melting and bolting points
  • Chemically reacts with other elements to form predictable products

Sulfur is made up of a consistent and uniform composition of sulfur atoms. A sample of sulfur is made up of 100% sulfur atoms.

In its solid state, it ordinarily exists as a yellow crystalline substance with a chemical structure S8. Other allotropes besides S8 include S7, which gives sulfur its yellow color, and S12 and S18.

Generally, sulfur reacts to form sulfides, sulfites, sulfates, nitrides, and oxides. The most common industrial use is manufacturing sulfuric acid (H2SO4).

A chemical reaction with hydrogen form hydrogen sulfide (H2S), a poisonous and corrosive gas. Hydrogen sulfide is well known for its characteristic awful smell of rotten eggs.

Also, sulfur reacts with most metals except gold and platinum to create compounds such as galena (lead sulfide, PbS), pyrite (iron disulfide, FeS2), blende (zinc sulfide, ZnS), and chalcopyrite (copper iron sulfide, CuFeS2).

Sulfur also has a fixed melting and boiling point. The nonmetallic substance melts into a dark and viscous liquid at 115.21 ° C (239.38 ° F) and boils at 444.6 ° C (832.3 ° F).

Is sulfur a homogeneous mixture?

Sulfur is not a homogenous mixture. In essence, a homogeneous mixture has the following properties:

  • It contains different kinds of elements, compounds, or both
  • The constituents don’t bond chemically, rather combine physically
  • It has variable composition; hence no definite melting or boiling points
  • Can be mechanically or physically separated into its constituent elements

Sulfur exists as a combination of only sulfur atoms. It is stable in normal conditions and naturally found in its common allotropic form of S8.

Several sulfur atoms bond to create a stable crystalline structure. The nonmetallic substance cannot be broken down further by any chemical or physical means.

Since sulfur lacks all the features of a homogenous mixture, it can only be classified as a pure substance.

Take Away

Sulfur is a naturally existing element. The yellow nonmetallic substance is classified as a pure substance since it is composed only of sulfur atoms.

Also, the element cannot be broken down further through chemical or physical processes, has a definite atomic mass, has a fixed boiling and melting point, and reacts with other elements to form predictable compounds.

Sulfur cannot be classified as a homogenous mixture since it fails to meet any qualifying characteristics.

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