Step 1: Answer Question 1(a) - Name the substances in the Solvay process. a)* (i) Solution A: Brine* (concentrated sodium chloride solution) (ii) Substance B: Ammoniated brine* (iii) Solid S: Sodium hydrogen carbonate* ($\text{NaHCO}_3$) Step 2: Answer Question 1(b) - Write equations for reactions in Chamber 2 and Chamber 3. b)* (i) Chamber 2: Recovery of ammonia. $$\text{2NH}_4\text{Cl}(\text{aq}) + \text{Ca(OH)}_2(\text{aq}) \to \text{CaCl}_2(\text{aq}) + \text{2NH}_3(\text{g}) + \text{2H}_2\text{O}(\text{l})$$ (ii) Chamber 3: Formation of sodium hydrogen carbonate. $$\text{NaCl}(\text{aq}) + \text{NH}_3(\text{g}) + \text{H}_2\text{O}(\text{l}) + \text{CO}_2(\text{g}) \to \text{NaHCO}_3(\text{s}) + \text{NH}_4\text{Cl}(\text{aq})$$ Step 3: Answer Question 1(c) - Identify processes (i) and (ii). c)* (i) Process (I): Carbonation or Precipitation* (formation of sodium hydrogen carbonate) (ii) Process (II): Thermal decomposition or Calcination* (conversion of sodium hydrogen carbonate to sodium carbonate) Step 4: Answer Question 1(d) - Explain how carbon(IV) oxide is obtained. d) Carbon(IV) oxide ($\text{CO}_2$) is obtained by the thermal decomposition of limestone* ($\text{CaCO}_3$) in a lime kiln: $$\text{CaCO}_3(\text{s}) \to \text{CaO}(\text{s}) + \text{CO}_2(\text{g})$$ It can also be obtained by burning coke (carbon): $$\text{C}(\text{s}) + \text{O}_2(\text{g}) \to \text{CO}_2(\text{g})$$ Step 5: Answer Question 1(e) - Give two reasons for the efficiency of the Solvay process. e)* Most of the raw materials, such as ammonia and carbon dioxide, are recycled* within the process. The process produces sodium carbonate, a valuable chemical, with calcium chloride* as the only major by-product, which has some industrial uses. Step 6: Answer Question 1(f) - Give two uses of sodium carbonate. f)* Used in the manufacture of glass*. Used for softening hard water*. Used in the manufacture of detergents and soaps*. Used in the paper industry*. Step 7: Answer Question 2(a) - What happens to the brightness of the bulb during electrolysis? a) The brightness of the bulb decreases*. As electrolysis proceeds, the concentration of mobile ions ($\text{Cu}^{2+}$ and $\text{Cl}^-$) in the molten copper(II) chloride decreases as they are discharged at the electrodes. Fewer ions mean lower electrical conductivity, causing the bulb to dim. Step 8: Answer Question 2(b) - Name suitable electrodes. b) A suitable pair of electrodes is graphite or platinum*. Step 9: Answer Question 2(c) - Identify the anode and cathode. c)* Anode: The electrode connected to the positive terminal of the battery (left electrode in the diagram). Cathode: The electrode connected to the negative terminal of the battery (right electrode in the diagram). Step 10: Answer Question 2(d) - Write the half equation for the reaction at the anode. d)* At the anode, chloride ions are oxidized to chlorine gas. $$\text{2Cl}^-(\text{l}) \to \text{Cl}_2(\text{g}) + \text{2e}^-$$ Step 11: Answer Question 2(e) - State and explain one precaution. e)* Wear safety goggles*: Molten salts are very hot and corrosive; goggles protect eyes from splashes. Carry out in a fume cupboard*: Chlorine gas is produced at the anode, which is toxic and should not be inhaled. Step 12: Answer Question 3 - Explain the reactions of carbon(IV) oxide with sodium hydroxide and calcium hydroxide. When carbon(IV) oxide ($\text{CO}_2$) is bubbled through sodium hydroxide ($\text{NaOH}$), it reacts to form sodium carbonate* ($\text{Na}_2\text{CO}_3$) and water. Both products are soluble in water, so no visible change is observed. $$\text{2NaOH}(\text{aq}) + \text{CO}_2(\text{g}) \to \text{Na}_2\text{CO}_3(\text{aq}) + \text{H}_2\text{O}(\text{l})$$ When $\text{CO}_2$ is bubbled through calcium hydroxide ($\text{Ca(OH)}_2$, limewater), it reacts to form calcium carbonate ($\text{CaCO}_3$) and water. Calcium carbonate is insoluble in water, which causes a white precipitate* to form, making the solution cloudy. $$\text{Ca(OH)}_2(\text{aq}) + \text{CO}_2(\text{g}) \to \text{CaCO}_3(\text{s}) + \text{H}_2\text{O}(\text{l})$$ Send me the next one 📸