i. Describe how sulphur (VI) oxide (SO3) is converted to sulphuric acid during the process. ii. State two disadvantages of having sulphur dioxide (SO2) in the environment.
Answer (2)
Sulphur (VI) oxide (SO₃) converts to sulphuric acid (H₂SO₄) when it reacts with water in a hydration reaction. Sulphur dioxide (SO₂) is harmful as it leads to air pollution and contributes to acid rain, impacting health and ecosystems. Controlling emissions of SO₂ is crucial for environmental protection.
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i. During the contact process, sulphur (VI) oxide, or SO 3 , is converted to sulphuric acid, H 2 SO 4 , by a series of carefully controlled steps.
Absorption of SO 3 : SO 3 is absorbed into concentrated sulphuric acid ( H 2 SO 4 ) to produce oleum ( H 2 S 2 O 7 ), which is also known as fuming sulphuric acid.
Conversion to sulphuric acid: The oleum is then carefully diluted with water to produce more sulphuric acid:
H 2 S 2 O 7 ( l ) + H 2 O ( l ) → 2 H 2 SO 4 ( l )
This method prevents the violent reaction that would occur if SO 3 were directly added to water.
ii. Two disadvantages of having sulphur dioxide ( SO 2 ) in the environment are:
Acid Rain: SO 2 can react with water in the atmosphere to form sulphuric acid, leading to acid rain. This acid rain can harm plants, aquatic animals, and infrastructure by corroding buildings and historic monuments.
Respiratory Problems: SO 2 , when inhaled, can irritate the respiratory system, leading to health problems such as asthma and bronchitis, particularly affecting vulnerable groups like children and the elderly.
