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Difficulty: HardTetraoxosulfate(VI) Acid: Contact Process and Properties

Arrange the following sequential stages involved in the industrial manufacture of tetraoxosulfate(VI) acid via the Contact Process in their correct chronological order from initial raw material processing to final acid product formation:

  1. 1Combustion of molten sulfur in dry air to generate sulfur(IV) oxide (SO2SO_2) gas.
  2. 2Scrubbing and electrostatic precipitation to remove dust particles and catalyst poisons such as arsenic(III) oxide.
  3. 3Exothermic oxidation of sulfur(IV) oxide to sulfur(VI) oxide (SO3SO_3) over a vanadium(V) oxide (V2O5V_2O_5) catalyst at 450∘C450^\circ\text{C} and 1−2 atm1-2\text{ atm}.
  4. 4Absorption of sulfur(VI) oxide gas in concentrated (98%) tetraoxosulfate(VI) acid to produce pyrosulfuric acid (oleum, H2S2O7H_2S_2O_7).
  5. 5Controlled dilution of oleum with a calculated quantity of water to yield pure tetraoxosulfate(VI) acid.

Answer

The correct sequence of stages in the Contact Process is: (1) Combustion of sulfur to produce SO2SO_2, (2) Purification of SO2SO_2 gas to remove catalyst poisons, (3) Catalytic oxidation of SO2SO_2 to SO3SO_3 over V2O5V_2O_5, (4) Absorption of SO3SO_3 into concentrated H2SO4H_2SO_4 to form oleum (H2S2O7H_2S_2O_7), and (5) Controlled dilution of oleum with water to produce concentrated H2SO4H_2SO_4.
The Contact Process progresses in five logical stages: sulfur combustion to generate SO2SO_2, gas purification to protect the catalyst, catalytic oxidation of SO2SO_2 to SO3SO_3 over V2O5V_2O_5, absorption of SO3SO_3 into concentrated H2SO4H_2SO_4 to produce oleum (H2S2O7H_2S_2O_7), and finally hydration of oleum with water to yield pure H2SO4H_2SO_4.

Step-by-Step Solution

1
Identify the initial feedstock generation phase
Elemental sulfur is burned in excess dry air to form SO2SO_2 (S(s)+O2(g)→SO2(g)S_{(s)} + O_{2(g)} \rightarrow SO_{2(g)}).
Sulfur(IV) oxide gas must be produced first before subsequent catalytic oxidation can occur.
2
Determine the necessary gas conditioning and purification step
The SO2SO_2 stream is washed, dried, and passed through electrostatic precipitators to eliminate impurities like As2O3As_2O_3.
Arsenic impurities deactivate (poison) the vanadium(V) oxide catalyst if not removed prior to entering the catalytic converter.
3
Identify the core catalytic conversion reaction
SO2SO_2 reacts reversibly with O2O_2 over V2O5V_2O_5 at 450∘C450^\circ\text{C} and 1−2 atm1-2\text{ atm} to form SO3SO_3 (2SO2(g)+O2(g)⇌2SO3(g)2SO_{2(g)} + O_{2(g)} \rightleftharpoons 2SO_{3(g)}).
This key reversible exothermic step converts sulfur(IV) oxide to sulfur(VI) oxide under optimal yield conditions.
4
Identify the absorption mechanism for SO3SO_3
SO3SO_3 gas is dissolved in 98% concentrated H2SO4H_2SO_4 to form oleum (SO3(g)+H2SO4(l)→H2S2O7(l)SO_{3(g)} + H_2SO_{4(l)} \rightarrow H_2S_2O_{7(l)}).
Direct addition of SO3SO_3 to water generates enormous heat, causing the water to vaporize and create a fog of acid mist that will not condense easily.
5
Determine the final product hydration stage
Oleum is diluted with water to generate H2SO4H_2SO_4 of desired concentration (H2S2O7(l)+H2O(l)→2H2SO4(l)H_2S_2O_{7(l)} + H_{2}O_{(l)} \rightarrow 2H_2SO_{4(l)}).
Diluting oleum produces pure tetraoxosulfate(VI) acid safely without fog or mist formation.

Key Concept

Sequential chemical steps, conditions, and process rationale of the industrial Contact Process for tetraoxosulfate(VI) acid production
Estimated Time:2m 0s
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Topics

Tetraoxosulfate(VI) Acid: Contact Process and Properties

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