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Question 30 — Industrial Chemistry (25 marks) (a) (i) Identify ONE use of sulfuric acid in industry - HSC - SSCE Chemistry - Question 30 - 2003 - Paper 1
Question 30
Question 30 — Industrial Chemistry (25 marks) (a) (i) Identify ONE use of sulfuric acid in industry. (ii) One of the starting materials used for preparing sulfur... show full transcript
Worked Solution & Example Answer:Question 30 — Industrial Chemistry (25 marks) (a) (i) Identify ONE use of sulfuric acid in industry - HSC - SSCE Chemistry - Question 30 - 2003 - Paper 1
Step 1
Step 2
Describe the process used to extract sulfur from mineral deposits.
Answer
The Frasch process is used to extract sulfur from underground deposits. In this process, superheated water and air are injected into a sulfur deposit. The heat melts the sulfur, forming a liquid, which is then pumped to the surface. The injected air oxidizes any sulfur-containing minerals, ensuring that only pure sulfur is extracted.
Step 3
Describe ONE precaution you took to minimise hazards, or to dispose of reactants and products safely.
Answer
During my investigation, I wore protective goggles and gloves to minimize hazards associated with the handling of sodium chloride and the products formed during electrolysis, ensuring safe disposal of any chemicals used.
Step 4
Outline the procedure you used to identify the products of electrolysis of sodium chloride.
Answer
To identify the products of electrolysis of sodium chloride, I set up an electrolytic cell, immersing two electrodes in the sodium chloride solution. I connected the electrodes to a power source and observed the reaction. Chlorine gas was produced at the anode, evidenced by the distinct smell and formation of bubbles, while hydrogen gas was produced at the cathode.
Step 5
Analyse how an understanding of the structure and cleaning action of soaps led to the development of synthetic detergents.
Answer
An understanding of the molecular structure of soaps, which have hydrophobic (water-repellent) tails and hydrophilic (water-attracting) heads, led chemists to develop synthetic detergents that mimic this structure. These detergents are designed to be effective in soft and hard water conditions, providing enhanced cleaning action compared to traditional soaps.
Step 6
Step 7
Describe TWO methods that could be used to increase the yield of nitrogen dioxide.
Answer
To increase the yield of nitrogen dioxide, one could:
- Increase the pressure of the reaction mixture, thus favoring the formation of the products according to Le Chatelier’s principle.
- Remove nitrogen dioxide gas as it is formed to shift the equilibrium towards the products.
Step 8
Calculate the equilibrium constant for the reaction. Show all relevant working.
Answer
Initially, we have 0.25 mol NO and 0.12 mol O2. At equilibrium, there is 0.05 mol remaining for NO. Therefore, the change in mol for NO is 0.25 - 0.05 = 0.20 mol, which means we produce 0.10 mol of NO2 (as per the stoichiometry of the reaction). Thus,
Initial: NO = 0.25 mol, O2 = 0.12 mol, NO2 = 0 Change: NO = -0.20 mol, O2 = -0.10 mol, NO2 = +0.10 mol Equilibrium: NO = 0.05 mol, O2 = 0.02 mol, NO2 = 0.10 mol.
The equilibrium expression is: K_c = rac{[NO_2]^2}{[NO]^2[O_2]} = rac{(0.10)^2}{(0.05)^2(0.02)} = rac{0.01}{0.0025 imes 0.02} = 100
Step 9
Assess how environmental issues have been addressed in an industrial method of production of an acid, and an industrial method of production of a base.
Answer
In the production of sulfuric acid, environmental concerns are addressed through the implementation of pollution control technologies that capture sulfur dioxide emissions, thus reducing air pollution. Additionally, in the production of sodium hydroxide, waste management practices are instituted to ensure that byproducts are treated safely and do not contaminate water sources.