CP2 Preparation of a Standard Solution and Titration

• What is a standard solution?

  Solution with known concentration
• The exact concentration of the solute in a standard solution must be accurately determined
• A standard solution must maintain its concentration over time and under standard storage conditions.
• What is the formula to calculate the required mass of a solute for a standard solution?

  $Mass =$$Concentration × Volume × Molar Mass$
• Steps to calculate the required mass of a solute for a standard solution

  1️⃣ Determine the desired concentration

  2️⃣ Identify the target volume

  3️⃣ Find the molar mass of the solute

  4️⃣ Use the formula to calculate the mass
• To prepare 250 mL of a 0.1 mol/L NaCl standard solution, the molar mass of NaCl is 58.44 g/mol.
• How many grams of NaCl are needed to prepare 250 mL of a 0.1 mol/L solution?

  1.461 g
• To prepare a standard solution, you should weigh out the solute and dissolve it in distilled water.
• Steps to prepare a standard solution in a volumetric flask

  1️⃣ Weigh out the solute

  2️⃣ Transfer the solute to the flask

  3️⃣ Add water until two-thirds full

  4️⃣ Swirl to dissolve the solute

  5️⃣ Fill to the calibration mark

  6️⃣ Mix thoroughly
• In the example given, 1.461 g of NaCl is used to prepare a standard solution in a 250 mL volumetric flask.
• What is the formula to calculate the required mass of solute?

  $Mass =$$Concentration × Volume × Molar Mass$
• The desired concentration in the formula is measured in mol/L
• What unit is used to measure the target volume in the formula?

  Liters
• The molar mass of the solute is measured in g/mol.
• Steps to calculate the required mass of solute

  1️⃣ Determine the desired concentration

  2️⃣ Identify the target volume

  3️⃣ Find the molar mass of the solute

  4️⃣ Calculate the mass using the formula
• To prepare 250 mL of 0.1 mol/L NaCl, the required mass is 1.461 g
• What equipment is needed to weigh out the solute accurately?

  Balance
• Match the step with the equipment needed to dissolve the solute in a volumetric flask:

  Weigh out solute ↔️ Balance

  Transfer solute ↔️ Volumetric flask, Funnel

  Add distilled water ↔️ Distilled water bottle

  Fill to calibration mark ↔️ Dropper
• When dissolving solute in a volumetric flask, it should be filled to two-thirds with distilled water first.
• When filling a volumetric flask to the calibration mark, use a dropper
• Steps to perform a titration

  1️⃣ Prepare a standard solution

  2️⃣ Set up the titration apparatus

  3️⃣ Add indicator

  4️⃣ Titrate slowly

  5️⃣ Monitor the end point

  6️⃣ Record burette readings

  7️⃣ Repeat the titration
• What is a standard solution defined as?

  A solution with known concentration
• A standard solution must be made from a solute of high purity
• A standard solution is a solution with a known concentration
• A standard solution maintains its concentration over time
• What does high purity of the solute in a standard solution ensure?

  Accurate concentration
• A 0.1 mol/L NaCl solution is an example of a standard solution.
• What formula is used to calculate the required mass of a solute for a standard solution?

  $Mass =$$Concentration × Volume × Molar Mass$
• Steps to calculate the required mass of a solute

  1️⃣ Determine the concentration of the solution

  2️⃣ Identify the desired volume of the solution

  3️⃣ Find the molar mass of the solute

  4️⃣ Calculate the required mass using the formula
• What is the required mass of NaCl to prepare 250 mL of a 0.1 mol/L solution?

  1.461 g
• To prepare a standard solution, the solute must be dissolved in a volumetric flask.
• Steps to dissolve a solute in a volumetric flask

  1️⃣ Weigh the required amount of solute

  2️⃣ Transfer the solute into the volumetric flask

  3️⃣ Add distilled water to two-thirds full

  4️⃣ Swirl the flask to dissolve the solute

  5️⃣ Fill to the calibration mark with distilled water

  6️⃣ Invert the flask to mix thoroughly
• What volume of distilled water is needed to prepare a 0.1 mol/L NaCl solution in a 250 mL volumetric flask?

  250 mL
• The meniscus in a volumetric flask must align with the calibration mark at eye level
• A titration is performed to determine the concentration of an unknown analyte.
• Steps to perform a titration

  1️⃣ Prepare the standard solution

  2️⃣ Set up the apparatus with analyte in a conical flask

  3️⃣ Add a suitable indicator

  4️⃣ Titrate slowly, swirling continuously

  5️⃣ Observe the end point

  6️⃣ Record burette readings

  7️⃣ Calculate analyte concentration
• How is the volume of titrant used in a titration calculated?

  Final reading - Initial reading
• What is the average titrant volume in the example provided?

  22.53 mL