Sulphur and Sulphuric Acid Flashcards
What is the oxidation state of sulfur in its compounds?
Sulfur belongs to Group VIA and has an oxidation state of +6.
Describe the physical properties of sulfur.
Sulfur is a yellow, tasteless, nearly odorless, insoluble nonmetal. It exists as an S8 ring in its most stable form.
Name the two allotropes of sulfur and their characteristics.
Orthorhombic sulfur: Most stable form with puckered, crown-like S8 rings.
Monoclinic sulfur: Contains S8 rings but has a different crystal structure
What are the natural sources of sulfur?
Combined states: Natural sulfates (e.g., BaSO4, CaSO4·2H2O) and sulfides (e.g., FeS2, CuS).
Free state: Found in underground deposits and volcanic areas (brimstone).
What process replaced iron pyrites as a source for sulfur extraction?
The Frasch process replaced iron pyrites, utilizing sulfur’s low melting point for extraction.
How does the Frasch process work?
It uses superheated water to melt sulfur underground. Compressed air forces the molten sulfur to the surface through concentric pipes.
What are the two main industrial processes for producing sulfuric acid?
Chamber Process: Produces dilute acid (62%-78% H2SO4).
Contact Process: Produces purer and more concentrated acid but requires cleaner raw materials and expensive catalysts.
Summarize the key reactions in sulfuric acid production.
SO2 + ½ O2 → SO3 (Oxidation of sulfur dioxide).
SO3 + H2O → H2SO4 (Formation of sulfuric acid).
What catalysts are used in the Contact Process?
Initially platinum (Pt), but now vanadium pentoxide (V2O5) is commonly used due to its resistance to poisons like arsenic.
What are the physical properties of sulfuric acid?
Sulfuric acid is a colorless, viscous, oily, and extremely corrosive liquid. It has a strong affinity for water.
How does concentrated sulfuric acid react with metals?
- Cold concentrated acid reacts poorly with common metals.
- Hot concentrated acid acts as an oxidizing agent, releasing SO2 gas.
Why is sulfuric acid called “oil of vitriol”?
It is an older term referring to its oily appearance and strong corrosiveness.
List some industrial applications of sulfur.
- Vulcanization of rubber.
- Production of fertilizers.
- Manufacture of gunpowder, matches, and fireworks.
- Used as fungicide, insecticide, and fumigant.
What is the major use of sulfuric acid?
The largest use (65%) is in the production of fertilizers, especially superphosphate of lime and ammonium sulfate.
Mention other uses of sulfuric acid.
- In making chemicals (e.g., hydrochloric acid, synthetic detergents).
- Petroleum refining.
- Metal processing (e.g., pickling of iron and steel).
- Electrolyte in lead-acid storage batteries.
How does sulfur contribute to acid rain?
Sulfur dioxide (SO2) from burning sulfur reacts with water in the atmosphere to form sulfuric acid, contributing to acid rain.
What measures are in place to reduce SO2 emissions in the Contact Process?
Double-absorption systems and scrubbers are used to reduce SO2 emissions, meeting strict regulations like those in the U.S.
What are the advantages of the Contact Process over the Chamber Process?
- Produces more concentrated sulfuric acid.
- Requires less energy.
- More efficient and environmentally friendly.
What is oleum, and where is it used?
Oleum is fuming sulfuric acid (sulfur trioxide dissolved in H2SO4). It is used in the Contact Process to produce concentrated sulfuric acid.
What are the environmental implications of sulfur emissions?
Sulfur emissions contribute to acid rain, impacting soil, water bodies, and ecosystems
