Question 1: Define a titration and explain its purpose in quantitative chemistry.

Answer: A titration is a laboratory technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration until the reaction is complete, as indicated by a colour change or other endpoint.

Question 2: Describe the role of an indicator in a titration.

Answer: An indicator is a chemical that changes colour at the endpoint of a titration, signalling that the reaction is complete.

Question 1: Explain the significance of the titration curve and how it relates to the endpoint.

Answer: The titration curve shows the pH change as titrant is added. The endpoint is identified at the steepest part of the curve, indicating the completion of the neutralisation reaction.

Question 2: Calculate the concentration of an unknown acid if 25.0 cm³ of it requires 30.0 cm³ of 0.100 mol/dm³ sodium hydroxide (NaOH) to neutralise.

Answer: Using the formula: C₁V₁ = C₂V₂, where C₁ is the concentration of acid, V₁ its volume, C₂ the concentration of NaOH, and V₂ its volume. C₁ = (C₂ × V₂) / V₁ = (0.100 mol/dm³ × 30.0 cm³) / 25.0 cm³ = (0.100 mol/dm³ × 30.0) / 25.0 = 0.120 mol/dm³

Question 3: If 50.0 cm³ of a solution of sodium carbonate reacts exactly with 25.0 cm³ of hydrochloric acid, what is the molarity of the sodium carbonate solution? (Molar mass of Na₂CO₃ = 106 g/mol, and it reacts with HCl in a 1:2 molar ratio).

Answer: Given: V_Na2CO3 = 50.0 cm³, V_HCl = 25.0 cm³, M_HCl unknown, M_Na2CO3 = 106 g/mol. From the balanced equation: Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂. C_Na2CO3 × V_Na2CO3 = 0.5 × C_HCl × V_HCl Assuming HCl concentration is known or given, students should apply the formula accordingly. Without HCl molarity, an example value can be assumed for calculation purposes. For example, if HCl is 0.1 mol/dm³: C_Na2CO3 = (0.5 × 0.1 mol/dm³ × 25.0 cm³) / 50.0 cm³ = 0.025 mol / 50.0 cm³ = 0.0005 mol/cm³ = 0.5 mol/dm³.

Question 4: A student titrates sulphuric acid with sodium hydroxide and records a titre volume of 24.5 cm³ using 0.1 mol/dm³ NaOH. How many moles of H₂SO₄ are present in 50.0 cm³ of the acid sample?

Answer: Number of moles of NaOH used: = 0.1 mol/dm³ × 24.5 cm³ = 0.1 mol/dm³ × 0.0245 dm³ = 0.00245 mol. From the balanced equation: H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O. Moles of H₂SO₄ = 0.5 × moles of NaOH = 0.5 × 0.00245 mol = 0.001225 mol. In 50.0 cm³ (0.05 dm³) of the acid, the concentration of H₂SO₄ = 0.001225 mol / 0.05 dm³ = 0.0245 mol/dm³.

Question 1: List three safety precautions to observe during a titration experiment.

Answer: Wear safety goggles and gloves, handle acids and bases carefully to avoid spills, and ensure proper disposal of chemicals after the experiment.

Question 2: Identify three variables that can affect the accuracy of a titration and suggest how to control them.

Answer: Variables include the concentration of solutions, the endpoint detection (colour change), and the measurement of volumes. Control by using standard solutions, consistent endpoint indicators, and calibrated burettes.

Question 3: Describe how you would perform a titration to determine the concentration of an unknown acid solution in a laboratory setting.

Answer: First, rinse and fill a burette with a standardised sodium hydroxide solution. Pipette a known volume of the unknown acid into a conical flask and add a suitable indicator. Slowly add the NaOH from the burette to the acid while swirling until a permanent colour change indicates the endpoint. Record the volume of NaOH used. Repeat the process to obtain consistent readings. Use the titration data to calculate the concentration of the acid using the formula C₁V₁ = C₂V₂.

Question 1: Explain how titration is used in the pharmaceutical industry, particularly in the formulation of medicines.

Answer: Titration is used to accurately determine the concentration of active ingredients in medicines, ensuring correct dosages and quality control during manufacturing.