titrations

• What is a soluble salt?

  A soluble salt can be prepared by reacting an acid with a dilute solution of an alkali.
• What is the purpose of carrying out a titration in salt preparation?

  To determine the volumes of acid and alkali that must be mixed to obtain a solution containing only salt and water.
• What should be done after determining the correct proportions of acid and alkali in a titration?

  Mix the acid and alkali without including an indicator.
• What is the method used to produce pure dry crystals from a solution?

  Crystallisation followed by drying on a watch glass or in a warm oven.
• What apparatus is needed for carrying out a titration?

  • Pipette
  • Burette
  • Conical flask
  • Pipette filler
• What is the function of a pipette in a titration?

  To accurately measure the volume of a reactant before transferring it to a conical flask.
• What is the role of a burette in a titration?

  To add small, measured volumes of one reactant to the other reactant.
• Why is a pipette filler used?

  To use a pipette safely.
• What is the method for carrying out a titration with an acid and an alkali?

  Add a measured volume of sodium hydroxide to a conical flask, then add acid from the burette until the end-point is reached.
• What indicates that the end-point of a titration has been reached?

  When the indicator first permanently changes color.
• What are concordant titres?

  Concordant titres are results that lie within 0.10 cm³ or less of each other.
• How should results from a titration be recorded?

  In a suitable table, with readings recorded to two decimal places.
• How do you calculate the mean titre from titration results?

  By averaging the concordant titres obtained.
• What is the formula for calculating the mean titre?

  Mean titre = (sum of concordant titres) / (number of concordant titres).
• What is the aim of the required practical in titration?

  To determine the reacting volumes of solutions of an acid and alkali by titration.
• What must be considered when planning a titration practical?

  Which apparatus to use, which reagents to use, and hazards and precautions.
• What reagents are used in the titration practical?

  • An acid (hydrochloric, sulfuric, or nitric) of unknown concentration
  • Sodium hydroxide solution of known concentration
  • A suitable indicator (e.g., methyl orange or phenolphthalein)
• What precautions should be taken when handling dilute sodium hydroxide solution?

  Wear gloves and eye protection, and use a pipette filler.
• What should be done to reduce the risk of spilling hydrochloric acid while filling the burette?

  Fill the burette slowly below eye level, using a funnel.
• What is the first step in carrying out the practical for titration?

  Add 25 cm³ of alkali to a clean conical flask using a pipette.
• How should the results of a titration be recorded?

  In a suitable table, with readings recorded to two decimal places.
• What is the significance of the titre in titration results?

  The titre is the volume added, calculated as the difference between the end and start readings.
• What is the balanced equation for the reaction between sodium hydroxide and hydrochloric acid?

  NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l)
• How do you calculate the amount of sodium hydroxide in moles?

  Amount of sodium hydroxide = concentration in mol/dm³ × volume in dm³.
• What is the mole ratio between sodium hydroxide and hydrochloric acid in their reaction?

  The mole ratio is 1:1.
• How do you calculate the concentration of hydrochloric acid in mol/dm³?

  Concentration in mol/dm³ = amount of solute in mol / volume in dm³.
• How do you calculate the concentration of hydrochloric acid in g/dm³?

  Mass = relative formula mass × amount.
• What is the relative formula mass of HCl?

  Relative formula mass of HCl = 1 + 35.5 = 36.5.
• How do you calculate the volume of sulfuric acid needed in a titration?

  Volume in dm³ = amount of solute in mol / concentration in mol/dm³.
• What is the mole ratio between sodium hydroxide and sulfuric acid in their reaction?

  The mole ratio is 2:1.
• How do you calculate the amount of sodium hydroxide needed to neutralize sulfuric acid?

  Use the mole ratio from the balanced equation to find the amount of sulfuric acid needed.
• How do you find the volume of sulfuric acid needed to neutralize a given amount of sodium hydroxide?

  Calculate the amount of sodium hydroxide in moles and use the mole ratio to find the volume of sulfuric acid.
• What are the steps involved in calculating the concentration of a solution from titration results?

  1. Calculate the amount of solute in moles.
  2. Use the balanced equation to find the mole ratio.
  3. Calculate the concentration in mol/dm³.
  4. Convert to g/dm³ if needed.