Sulfur Trioxide Formula – Structure, Properties, Uses, Sample Questions

Sulfur trioxide, or SO₃, is a chemical compound with the chemical formula SO₃. Sulfur trioxide comes in a variety of forms, each with its own molecular species and crystalline structure. It is colourless in liquid form and emits fumes in ambient settings. It is a highly reactive chemical that is also a strong oxidizer and a fire danger. In comparison to selenium dioxide, it is a thermodynamically unstable molecule.

Structure of Sulfur Trioxide

1. SO₃ is a D₃h symmetry trigonal planar molecule in its gaseous state, as predicted by VSEPR theory. As a result, SO₃ is classified as a member of the D₃h point group.
2. The sulphur atom has an oxidation state of +6 and a formal charge of 0 according to electron-counting formalism. Without using the d-orbitals, the Lewis structure holds one S=O double bond and two S–O dative bonds.
3. The electrical dipole moment of gaseous sulphur trioxide is 0. This is due to the 120-degree angle between the S-O bonds.

Properties of Sulfur Trioxide

Physical Properties

Chemical formula	SO3
Density	1.92 g/cm3
Molecular mass	80.066 gm/mol
Boiling point	44.9 °C
Melting point	16.9 °C
Odour	No odour
Appearance	Colorless to white crystalline solid
Complexity	61.8
Hydrogen bond acceptor	3
Solubility	Soluble in water

Chemical Properties

• Sulfuric acid is formed when sulphur trioxide combines with water.

SO₃ + H₂O → H₂SO₄

• When sulphur trioxide interacts with sodium hydroxide, sodium hydrogen phosphate is formed.

SO₃ + NaOH → NaHSO₄

Uses of Sulfuric Trioxide

1. It’s used as a bleaching agent to get rid of any leftover hydrogen peroxide or as a digesting agent to separate the pulp from lignin.
2. In the oxidation of sulphur dioxide to sulphur trioxide, it is used as a catalyst.
3. It’s a sulfuric acid-based powerful inorganic acid mist used in industry and commercial product manufacturing.
4. In the sulfonation reaction, it is a necessary reagent.
5. Photovoltaic cells and solar energy gadgets are made with this material.

Sample Questions

Question 1: What happens when Sulfur Trioxide and Water Mix?

Answer:

It takes a lot of heat to create sulfuric acid vigorously. This is the reaction that can be utilised to make sulfuric acid by converting metal sulphides or sulphur to SO₂, catalytically turning it to SO₃, and then reacting SO₃ with water.

However, by combining SO₃ gas with rather concentrated sulfuric acid, we can produce even more concentrated acid. As a result, we’re reacting to a low concentration of water in H₂SO₄, and the reaction is proportionately less intense.

Question 2: Why is Sulphur Trioxide Electrophilic in Nature?

Answer:

Sulphur can be bound two times to each of the three oxygens. The sulphur atom in the middle has a formal charge of zero, but the oxygens to which it is linked are exceedingly electronegative (they are known as electron hogs), therefore the sulphur atom in the middle has a partial plus charge on it. As a result, it will accept the electrons to compensate.

Question 3: What happens when Sulphur trioxide interacts with sodium hydroxide?

Answer:

Sodium hydrogen phosphate is generated when sulphur trioxide reacts with sodium hydroxide.

SO₃ + NaOH → NaHSO₄

Question 4: What are the uses of Sulfur Trioxide?

Answer:

• It’s utilised as a bleaching agent to remove any remaining hydrogen peroxide, as well as a digesting agent to separate pulp from lignin.
• It acts as a catalyst in the conversion of sulphur dioxide to sulphur trioxide.
• It’s a powerful inorganic acid mist made from sulfuric acid that’s employed in industry and commercial product manufacturing.
• It is a required reagent in the sulfonation reaction.
• This substance is used in photovoltaic cells and solar energy devices.

Question 5: What is Sulfur Trioxide?

Answer:

The chemical compound sulphur trioxide, or SO3, has the formula SO3. Sulfur trioxide is available in a number of different forms, each with its own molecular species and crystalline structure. In liquid form, it is colourless and releases odours in the environment. It’s a highly reactive compound that’s also a powerful oxidant and a potential fire hazard. It is a thermodynamically unstable compound as compared to selenium dioxide.

Question 6: Why SO₃ is acidic?

Answer:

Because sulphur is a non-metal, and we know that non-metal oxides are acidic in general. When SO₃ is dissolved in H₂O, the solution changes colour from blue to red, indicating that the solution is acidic.