Question 1: Define aqueous electrolysis and explain its basic principle.

Answer: Aqueous electrolysis is a process where an electric current is passed through water containing dissolved ions, causing chemical reactions at the electrodes to decompose compounds or produce substances. Its basic principle involves the movement of ions towards electrodes where oxidation and reduction occur.

Question 2: Describe one environmental application of aqueous electrolysis.

Answer: One application is the electrolysis of seawater to produce chlorine gas, which can be used for water purification or disinfecting surfaces, helping reduce the spread of waterborne diseases.

Question 1: What ions are involved when electrolysing an aqueous sodium chloride solution?

Answer: Sodium ions (Na+), chloride ions (Cl-), hydrogen ions (H+), and hydroxide ions (OH-).

Question 2: Explain why hydrogen gas is produced at the cathode during the electrolysis of water.

Answer: Hydrogen gas is produced at the cathode because water molecules gain electrons (reduction), producing hydrogen gas and hydroxide ions.

Question 3: Identify the oxidation and reduction processes occurring during aqueous electrolysis of sodium chloride solution.

Answer: Oxidation: Chloride ions (Cl-) lose electrons to form chlorine gas. Reduction: Water molecules gain electrons to produce hydrogen gas.

Question 1: Calculate the volume of hydrogen gas produced at the cathode when 96,500 coulombs of charge pass through water during electrolysis. (Use Faraday's constant: 96,500 C per mol of electrons, and 1 mol of H₂ gas occupies 22.4 L).

Answer: The amount of substance (mol) = total charge / Faraday's constant = 96,500 C / 96,500 C/mol = 1 mol. Volume of H₂ = 1 mol × 22.4 L = 22.4 litres.

Question 2: If 0.5 mol of chloride ions are electrolysed in aqueous solution, how many grams of chlorine gas are produced? (Atomic mass of Cl = 35.45 g/mol).

Answer: Chlorine gas produced = 0.5 mol × 70.9 g/mol (since Cl₂ has 2 Cl atoms) = 35.45 g.

Question 1: Describe the key safety precautions that should be taken when performing electrolysis involving aqueous solutions containing chlorine.

Answer: Proper ventilation to avoid inhaling chlorine gas, wearing protective gloves and goggles, working in a well-ventilated area, and avoiding contact with skin and eyes.

Question 2: Identify the variables that can be changed in an electrolysis experiment to increase the amount of hydrogen produced.

Answer: Increasing the current supplied, increasing the duration of electrolysis, using electrodes with larger surface area, and ensuring efficient contact between electrodes and solution.

Question 1: A company uses electrolysis to produce chlorine from seawater to disinfect drinking water. Discuss the environmental benefits and potential hazards of this process.

Answer: Benefits include effective disinfection, reduction of waterborne diseases, and production of useful chemicals like bleach. Hazards involve potential release of toxic chlorine gas into the environment, risks of accidents during handling, and the need for proper waste management to prevent ecological damage.

Question 2: In an industrial process, electrolysis is used to extract aluminium from bauxite ore. Explain how aqueous electrolysis differs from this process and why it is more environmentally sustainable.

Answer: Aqueous electrolysis involves dissolving salts in water and using electrical energy to decompose them, often at lower temperatures and with less environmental impact. In contrast, extracting aluminium from bauxite involves high-temperature electrolysis of molten cryolite, which consumes large amounts of energy and produces greenhouse gases. Aqueous electrolysis can be more sustainable due to lower energy requirements and fewer emissions.