Titrations

• What is a soluble salt prepared from?

  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 needed to obtain 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
• How can pure dry crystals be produced from the reaction?

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

  A pipette, burette, and conical flask
• Why is a pipette filler needed?

  To use a pipette safely
• What is the method for carrying out a titration?

  Use a pipette to add alkali, then add acid from a burette until the end-point is reached
• What indicates the end-point in a titration?

  When the indicator first permanently changes color
• What should be done if concordant titres are not obtained?

  Repeat the titration until concordant titres are achieved
• How should readings be recorded in a titration?

  To two decimal places, ending in 0 or 5
• What is a titre in the context of titration?

  The volume added, calculated as the difference between end and start readings
• What is the significance of concordant titres in titration results?

  They indicate reliable and accurate measurements
• How do you calculate the mean titre from titration results?

  By averaging the concordant titres
• What is the formula to calculate 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
• What must be worn for safety during the practical?

  Eye protection
• What should the practical plan address?

  Apparatus, reagents, hazards, risks, and precautions
• What are the reagents used in the titration practical?

  An acid of unknown concentration and sodium hydroxide of known concentration
• What is a hazard associated with dilute sodium hydroxide solution?

  It causes skin and serious eye irritation
• What precaution should be taken when using hydrochloric acid?

  Fill the burette slowly below eye level
• What is the first step in carrying out the practical?

  Add 25 cm$^3$ of alkali to a clean conical flask
• What should be done after adding the acid to the alkali in the conical flask?

  Swirl to mix
• How should results be recorded in the practical?

  In a suitable table
• What should be done if the titres are not concordant?

  Repeat the titration until concordant titres are obtained
• What is the formula for calculating concentration in mol/dm$^3$?


  Concentration in mol/dm$^3$ = amount of solute in mol / volume in dm$^3$
• How do you calculate the amount of sodium hydroxide in moles?

  Amount of sodium hydroxide = concentration × volume
• What is the mole ratio of NaOH to HCl in the balanced equation?

  1. 1
• How do you calculate the concentration of hydrochloric acid in mol/dm$^3$?


  Concentration in mol/dm$^3$ = amount of solute in mol / volume in dm$^3$
• What is the relative formula mass of HCl?

  36.5
• How do you calculate the mass of HCl from its concentration?

  Mass = relative formula mass × amount
• What is the concentration of hydrochloric acid in g/dm$^3$ if the mass is 4.56 g?


  1. 56 g/dm$^3$
• How do you calculate the volume of sulfuric acid needed in a titration?

  Volume in dm$^3$ = amount of solute in mol / concentration in mol/dm$^3$
• What is the mole ratio of NaOH to H$2$SO$4$ in the balanced equation?


  1. 1
• How do you calculate the amount of sulfuric acid needed from sodium hydroxide?

  0.00375 mol of H$2$SO$4$ reacts with 0.00750 mol of NaOH
• What is the final volume of sulfuric acid needed if 0.100 mol/dm$^3$ is used?


  37.5 cm$^3$
• What are the main steps in making salts from acids and alkalis?

  1. Carry out a titration to determine volumes of acid and alkali.
  2. Mix the acid and alkali in the correct proportions without an indicator.
  3. Produce pure dry crystals by crystallisation and drying.
• What are the key safety precautions when performing titrations?

  • Wear eye protection.
  • Use gloves when handling sodium hydroxide.
  • Fill burette below eye level to avoid spills.
• What is the process for calculating concentrations and volumes in titration?

  1. Calculate moles of the known solution.
  2. Use the mole ratio from the balanced equation.
  3. Calculate the concentration or volume of the unknown solution.