NaOH Concentration Determination by Titration

Onderzoekspracticum: Bepaling van NaOH-concentratie mbv Titratie

Attitudes (Attitudes Observed During the Experiment)

• Veiligheid:
  • Lab coat worn and closed properly.
  • Safety goggles worn.
  • Awareness of P- and H-phrases (hazard and precautionary statements).
  • Safe behavior towards fellow students.
• Orde en Netheid (Order and Cleanliness):
  • Glassware cleaned.
  • Work table and sink cleaned.
  • Waste sorted correctly.
  • All materials returned to their proper place.
• Werk (Work Ethic):
  • Proper use of materials.
  • Execution of the experiment.
  • Efficient collaboration.
  • No talking with other groups.
• Gedrag (Behavior):
  • Hair properly tied.
  • Book bag stored away.
  • Reflection on the experiment.

Doel van het Practicum (Purpose of the Experiment)

• Determine the concentration of sodium hydroxide (NaOH) by titration with a standardized hydrochloric acid (HCl) solution (0.10 mol/L).
• Learn how to use volumetric equipment: volumetric flask, pipette, pipette pump, burette.

Oriënteren - Onderzoeksvraag (Orientation - Research Question)

• Onderzoeksprobleem (Research Problem): Determine the concentration of sodium hydroxide by titration with a standardized HCl solution (0.10 mol/L). The NaOH solution is provided.

Onderzoeksvragen (Research Questions)

Voorbereiden (Preparation)

A - Informatie verzamelen = vooronderzoek (Gathering Information = Preliminary Research)

• Principle of titration.
• Principle of acid-base indicators.

B - Benodigdheden (Materials)

• Materiaal (Equipment):
  • Burette
  • Stand
  • Burette clamp
  • Erlenmeyer flask (250 mL)
  • Graduated cylinder (100 mL)
  • Pipette (10 mL)
  • Funnel
  • White card (as background)
• Stoffen (Chemicals):
  • Phenolphthalein
  • Distilled water
  • NaOH solution (H315-319, P280.1+3-305+351+338)
  • HCl solution 0.10 mol/L (no H- and P-phrases)
    • H-phrases (Hazard statements) indicate the nature and severity of the hazards associated with a chemical substance or mixture.
    • P-phrases (Precautionary statements) provide recommended measures to minimize or prevent adverse effects resulting from exposure to a chemical substance or mixture.

Uitvoeren (Execution/Procedure)

• Werkwijze (Method):
  • Using a pipette, transfer exactly 10 mL of the NaOH solution into an Erlenmeyer flask.
  • Add a few drops of phenolphthalein indicator and homogenize (swirl to mix).
  • Fill the burette with the 0.10 mol/L HCl solution.
  • Record the initial reading of the HCl solution in the burette.
  • Titrate until the solution turns colorless.
  • Record the final reading of the HCl solution in the burette.
  • Perform the titration at least three times and calculate the average volume of HCl added.
  • Drain the burette completely. Rinse the burette by filling it with tap water and letting it drain.
• Proefopstelling (Experimental Setup): (Draw a diagram and label the parts)

Meetgegevens (Measurements)

Berekeningen (Calculations)

• Calculate the concentration of NaOH in the solution expressed in mol/L.
• Calculate the concentration of NaOH in the solution expressed in m/V% (mass/volume percentage).
  • m/V % =
    umerator{mass of solute (g)}{volume of solution (mL)} * 100

Rapporteren - Reflecteren (Reporting - Reflection)

Evalueren uitvoering (Evaluate Execution)

• Does the calculated concentration correspond to the value stated on the label? If not, what could be the reasons for this?