Question 1: Explain what a titration is and describe its purpose in quantitative chemistry.

Answer: A titration is a laboratory process used to determine the concentration of an unknown solution by gradually adding a solution of known concentration until the reaction is complete. Its purpose is to find the precise concentration of acids, bases, or other reactive solutions.

Question 1: What is the neutralisation reaction involved in titrations between acids and bases?

Answer: Neutralisation is a reaction where an acid reacts with a base to produce water and a salt, typically represented as acid + base → salt + water.

Question 2: Identify the typical indicators used in titrations and explain their role.

Answer: Indicators such as phenolphthalein or methyl orange are used to show the end point of titration by changing colour, indicating that neutralisation has occurred.

Question 1: A 25.0 cm³ sample of hydrochloric acid (HCl) is titrated with 0.100 mol/dm³ sodium hydroxide (NaOH). It takes 30.0 cm³ of NaOH to neutralise the acid. Calculate the concentration of the hydrochloric acid.

Answer: Concentration of HCl = (Molarity of NaOH × Volume of NaOH) / Volume of HCl = (0.100 mol/dm³ × 30.0 cm³) / 25.0 cm³ = (0.100 mol/dm³ × 0.030 dm³) / 0.025 dm³ = 0.120 mol/dm³

Question 2: If 20.0 cm³ of sulphuric acid (H₂SO₄) reacts with 40.0 cm³ of 0.150 mol/dm³ sodium hydroxide, what is the concentration of the sulphuric acid?

Answer: Using the reaction: H₂SO₄ + 2 NaOH → Na₂SO₄ + 2 H₂O Moles of NaOH = 0.150 mol/dm³ × 0.040 dm³ = 0.006 mol Moles of H₂SO₄ = 0.006 mol / 2 = 0.003 mol Concentration of H₂SO₄ = 0.003 mol / 0.020 dm³ = 0.15 mol/dm³

Question 1: List three safety precautions that should be followed when performing a titration experiment.

Answer: Wear safety goggles and gloves, handle acids and bases with care, and ensure the apparatus is properly secured and stable.

Question 2: Identify two variables that must be controlled during a titration experiment.

Answer: The concentration of the solutions and the drop rate of titrant addition.

Question 1: During a titration, 25.0 cm³ of an unknown acid required 28.0 cm³ of 0.200 mol/dm³ sodium hydroxide to reach the end point. Calculate the concentration of the acid.

Answer: Moles of NaOH = 0.200 mol/dm³ × 0.028 dm³ = 0.0056 mol Assuming 1:1 reaction, moles of acid = 0.0056 mol Concentration of acid = 0.0056 mol / 0.025 dm³ = 0.224 mol/dm³

Question 1: A student titrates 50.0 cm³ of an unknown acid solution with 0.150 mol/dm³ sodium hydroxide. It takes 35.0 cm³ of the NaOH to neutralise the acid. The acid is known to be monoprotic. Calculate the concentration of the acid solution. Show all working and explain each step.

Answer: First, calculate moles of NaOH: 0.150 mol/dm³ × 0.035 dm³ = 0.00525 mol. Since the acid is monoprotic, moles of acid = moles of NaOH = 0.00525 mol. Then, concentration of acid = moles / volume in dm³ = 0.00525 mol / 0.050 dm³ = 0.105 mol/dm³. This is the concentration of the unknown acid solution.

Question 1: Describe an industry or daily life scenario where titrations are essential, and explain why accurate titration calculations are important in that context.

Answer: In the pharmaceutical industry, titrations are used to determine the concentration of active ingredients in medicines, ensuring correct dosage. Accurate calculations are vital to guarantee drug efficacy and safety.