This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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Here are the solutions to the questions: a) (i) Outline 3 key steps to prepare the standard solution. 1. Weigh the required mass of solid sodium carbonate accurately using an electronic balance. 2. Dissolve the solid in a small amount of distilled water in a beaker and transfer the solution quantitatively to a 250 cm³ volumetric flask. 3. Add distilled water to the volumetric flask until the bottom of the meniscus reaches the 250 cm³ mark, then stopper and invert to mix thoroughly. a) (ii) State one precaution in preparing the standard solution. • Ensure that the meniscus is read at eye level to avoid parallax error when making up to the mark. b) (i) Identify the main apparatus in which you would prepare the standard solution. • 250 cm³ volumetric flask b) (ii) Calculate the mass of solid sodium carbonate that you would use to prepare the 0.1 M Na_2CO_3. (Molar mass of sodium carbonate is 106 g/mol) Step 1: Calculate the number of moles of Na_2CO_3 needed. Moles = Concentration × Volume (in dm^3) Moles = 0.1 mol/dm^3 × (250)/(1000) dm^3 Moles = 0.1 mol/dm^3 × 0.250 dm^3 = 0.025 mol Step 2: Calculate the mass of Na_2CO_3. Mass = Moles × Molar mass Mass = 0.025 mol × 106 g/mol Mass = 2.65 g b) (iii) Suggest a piece of equipment, not given above, that is used to weigh the solid sodium carbonate. • Electronic balance c) (i) Name the technique used to determine the concentration of dilute sulphuric acid using the standard solution. • Titration c) (ii) Explain why it is better to place the dilute sulphuric in the burette. • The dilute sulphuric acid is the analyte (solution of unknown concentration) and is typically placed in the burette to be added dropwise, allowing for precise measurement of the volume required to neutralize the known volume of standard solution. c) (iii) Suggest an appropriate cleaning procedure for the: • Burette: Rinse with distilled water, then rinse with the dilute sulphuric acid it will contain. • Pipette: Rinse with distilled water, then rinse with the sodium carbonate solution it will contain. d) Determine the concentration of the acid in mol/dm³. Given: Concentration of Na_2CO_3 (C_B) = 0.1 M Volume of Na_2CO_3 (V_B) = 25 cm³ = 0.025 dm³ Volume of H_2SO_4 (V_A) = 20 cm³ = 0.020 dm³ Balanced equation: H_2SO_4 + Na_2CO_3 Na_2SO_4 + CO_2 + H_2O The mole ratio of H_2SO_4 : Na_2CO_3 is 1:1. Step 1: Calculate the moles of Na_2CO_3 used. Moles of Na_2CO_3 = C_B × V_B Moles of Na_2CO_3 = 0.1 mol/dm^3 × 0.025 dm^3 = 0.0025 mol Step 2: Determine the moles of H_2SO_4 reacted. Since the mole ratio is 1:1, Moles of H_2SO_4 = Moles of Na_2CO_3 = 0.0025 mol Step 3: Calculate the concentration of H_2SO_4. Concentration of H_2SO_4 = Moles of H_2SO_4Volume of H_2SO_4 (in dm^3) Concentration of H_2SO_4 = 0.0025 mol0.020 dm^3 Concentration of H_2SO_4 = 0.125 mol/dm^3 That's 2 down. 3 left today — send the next one.