Sulphate Ion Formula – Structure, Properties, Uses, Sample Questions

It is one of the most widely available chemical compounds on earth. It can be obtained from naturally occurring minerals since it is mostly found in the environment as a result of atmospheric and terrestrial processes. It is mostly available in the form of Sulphur released from erosion of evaporated deposits, sulfide-containing rocks and minerals, and even volcanoes. The Sulphate ion is widely used in the preparation of salts, peroxides, and acid derivatives.

What is Sulphate Ion?

Sulphate Ion or simply Sulphate (SO₄^-2) is consisting of one Sulphur ion and four oxygen ions which makes it a polyatomic molecule. Its empirical formula is SO₄^-2. This molecule is an anion having a –2 charge. The Sulphate ion is widely used in the preparation of salts, peroxides, and acid derivatives. 

It is made up of one Sulphur atom and two oxygen atoms. Oxygen is having the symbol O and its atomic number is 8. It is a highly reactive nonmetal and a good oxidizing agent. Usually, Oxygen is present as a diatomic gas with the formula O₂. The valency of Oxygen is 2. Sulphur is having the symbol S and its atomic number is 16. It is a nonmetallic compound and under normal conditions, its atoms are present as 8 atoms forming an S₈ molecule. Sulphur is present in the form of bright yellow crystals at room temperature. S₈ is a multivalent atom having 2 as a predominant valency.

Formula of Sulphate ion: 

Sulphate ion is basically made up of Sulphur and oxygen atoms. Sulphate ion is present in sulphuric acid which is called the king of chemicals since it is used in the preparation of most of the compounds. Sulphate can form a salt with a variety of elements like potassium, sodium, calcium, magnesium, and barium.  

Hence the formula of Sulphate Ion is SO₄^-2.

Structure of Sulphate ion

It is made up of one Sulphur atom and two oxygen atoms. It is having a structure of tetrahedral with sulphur situated at the center and four equivalent oxygen atoms are present around it. The Sulphur is in the +6 oxidation state and oxygen is -2 oxidation state. The Sulphate ion is carrying an overall charge of –2 so, it is unstable and is present in the resonant form.

It forms double bonds with two Oxygen atoms and single bonds with OH molecules. The bond length between Sulphur and oxygen in Sulphate atoms is 149 pm. The atoms are placed 109.5-degree angle.

Preparation of Sulphate ion

There are two laboratory preparation methods for Sulphate

• It can be prepared from the oxidation of metal sulphides in the presence of oxygen, heat, and catalyst.  

2Cu₂S + 5O₂ → 2CuSO₄ + 2CuO

ZnS + 2O₂ → ZnSO₄

• It also can be prepared by the reaction of metal hydroxide, metal oxide, and pure metals with sulphuric acid.

Ba(ClO₃)₂ + H₂SO₄ → 2 HClO₃ + BaSO₄

Zn + H₂SO₄ → ZnSO₄ + H₂

Cu(OH)₂ + H₂SO₄ → CuSO₄ + 2 H₂O  

CdCO₃ + H₂SO₄ → CdSO4 + H₂O + CO₂

Properties of Sulphate ion

Physical properties of Sulphate ion:

1. IUPAC name of Sulphate ion is Sulphate.
2. Melting point of Sulphate ion is 270.47 degree Celsius
3. The boiling point of the Sulphate ion is 623.89 degrees Celsius.
4. The molar mass of Sulphate ion is 96.06 gram per mole.
5. Most of the ionic Sulphates are highly soluble in water(Except Calcium Sulphate, strontium Sulphate, lead Sulphate, and barium Sulphate which are poorly soluble).
6. Vapour pressure of Sulphate ion is 0.00791 Pascal.
7. Radium Sulphate is the most insoluble Sulphate known so far.

Chemical properties of Sulphate ion:

• The most important property of Sulphate ion is that it can easily make bonds with metals.

2NaCl + H₂SO₄ → Na₂SO₄ + 2HCl

• Most commonly used test for the presence of Sulphate ions is the Rhodium Sulphate test.

2BaCl + H₂SO₄ → Ba₂SO₄ + 2HCl.

• It easily precipitates with the Sulphate ion giving white powder easily.
• Sulphate ion is present in the form of resonant structure enabling it to attract metals to form a bond.
• Even the Sulphate is having so many electrons present it is not willing to make the bond with other metals because the oxygen atoms present around the Sulphate atom act as ligands.
• Conjugate acid of Sulphate ion is sulphuric acid.
• Conjugate base of Sulphate ion is Sulphate.

Harmful effects and Safety measures for Sulphate Ion

• The harmful effects of Sulphate ion depend on the atom it is combined with two forms of Sulphate.
• Burning of fossil fuels and biomass can lead to acidity in the atmosphere and cause of acid rain.  
• This is because combustion of these Sulphate containing elements can lead to microscopic particles released into the air (aerosols).
• These aerosols can lead to dryness of skin, damage hair particles, and have hair with a negative charge.

Uses and Applications of Sulphate Ion

1. Vegetables need Sulphate ions for their growth and development which is provided in the form of Knapsack sprayer.
2. Sulphate is used widely in industries.
3. Gypsum (hydrated calcium Sulphate) is used in construction. 
4. Copper Sulphate is used as an electrolyte in galvanic cells in the laboratory and is also used as the most common algaecide.
5. iron Sulphate provides iron for living organisms and soil and many more.
6. Magnesium Sulphate is used in therapeutic baths.
7. Used as a detergent, emulsifier, and foaming agent.
8. Sulphate compounds are also used in daily use items like toothpaste, body sprays lotion makeup, soaps, and shampoos.

Sample Questions 

Question 1: Explain the structure of Sulphate ions.

Answer:

It is made up of one Sulphur atom and two oxygen atoms. It is having a structure of tetrahedral with Sulphur situated at the center and equivalent oxygen is present around it. The Sulphur is in the +6-oxidation state and oxygen is -2 oxidation state. The Sulphate ion is having an overall charge of –2. Since it is carrying a –2 charge over it, it is present in the resonant form. It forms double bonds with two Oxygen atoms and single bonds with OH molecule. The bond length between Sulphur and oxygen in a Sulphate atom is 149 pm. The atoms are placed 109.5-degree angle.

Question 2: Name the conjugate acid and base of the Sulphate ion.

Answer:

The Conjugate acid of the Sulphate ion is sulphuric acid and the Conjugate base of the Sulphate ion is Sulphate.

Question 3: List out some examples of the compounds that contain Sulphate ions.

Answer:

Here is the list:

• Sodium Lauryl Sulphate,
• Magnesium Sulphate,
• Gypsum,
• Copper Sulphate,
• Iron (II) Sulphate,
• Sodium Sulphate,
• Calcium Sulphate,
• Hydrogen Sulphate, and 
• Lead Sulphate, etc,

Question 4: What are the various of Sulphur?

Answer:

Sulphur comes in a variety of forms, including sulphur dioxide, sulphur trioxide, and sulfuric acid. In comparison to other elements, sulphur has a high potential for catenation and chemical reactivity. As a result, it may be converted into a variety of different formats.

Question 5: What are some allotropes of Sulphur?

Answer:

In the periodic table, sulphur is found in group 6 of solid nonmetals, with oxygen and other elements. Sulphur is the most reactive element after oxygen, especially at high temperatures, which aids in the breakdown of A-S bonds in S8 molecules. Sulphur interacts immediately with carbon, phosphorus, arsenic, and a variety of metals as it burns in the air. It is oxidized into SO₂ by oxidising acids, while alkalis dissolve it into sulphides and thiosulfate by reacting with H₂ and halogens. Sulphides are stable compounds, and many metals may be found in the form of sulphites in nature. Sulphur comes in rhombic, monoclinic, plastic, and amorphous allotropes.