Säure-Base-Titration mit Phenolphthalein

Bestimmung der Konzentration einer Säure mit einer Standardbase

Titrations Intermediate (High School) 45 Min. ~$15,00

Ziel

Die Konzentration einer unbekannten Salzsäurelösung durch Titration mit einer standardisierten Natriumhydroxidlösung unter Verwendung von Phenolphthalein als Indikator bestimmen.

Hintergrund

This classic acid-base titration demonstrates stoichiometric neutralization. HCl reacts with NaOH in a 1:1 molar ratio. Phenolphthalein turns pink above pH 8.2, providing a clear endpoint. Accurate burette technique and multiple trials are essential for reliable results.

Sicherheitswarnungen

  • NaOH is corrosive — avoid skin and eye contact
  • HCl is corrosive — handle with care
  • Wear safety goggles throughout
  • Wash any spills immediately with water

Erforderliche PSA

goggles gloves lab_coat

Materialien

  • Hydrochloric acid (HCl) (100 mL)
    Unknown concentration
  • Sodium hydroxide (NaOH) (100 mL)
    0.1M standardized
  • Phenolphthalein indicator (5 mL)
    1% in ethanol
  • Distilled water (500 mL)
    For rinsing

Ausrüstung

50 mL burette Burette stand and clamp 250 mL Erlenmeyer flask 25 mL pipette Pipette filler White tile Wash bottle

Durchführung

1

Rinse the burette with a small amount of NaOH solution, then fill it to the 0 mL mark. Record the exact starting volume.

5 Min. Handle NaOH carefully
2

Using the pipette and filler, transfer exactly 25.0 mL of the unknown HCl solution into the Erlenmeyer flask.

3 Min.
3

Add 2-3 drops of phenolphthalein indicator to the flask. The solution should remain colorless (acidic).

1 Min.
4

Place the flask on the white tile under the burette. Begin adding NaOH slowly while swirling the flask continuously.

5 Min.
5

As the endpoint approaches (pink color lingers longer), add NaOH drop by drop until a permanent pale pink color persists for 30 seconds.

5 Min.
6

Record the final burette reading. Calculate the volume of NaOH used.

2 Min.
7

Repeat the titration at least two more times for concordant results (within 0.10 mL).

15 Min.
8

Calculate the concentration of HCl using: C(HCl) = C(NaOH) x V(NaOH) / V(HCl).

5 Min.

Erwartete Ergebnisse

The endpoint should show a clear transition from colorless to a persistent pale pink. Concordant titre values (within 0.10 mL) indicate good technique. The calculated concentration should match the expected value within experimental error.

Aufräumen

Drain the burette and rinse with distilled water. Neutralize waste solutions before disposal. Rinse all glassware thoroughly.

Details

Kategorie
Titrations
Schwierigkeit
Intermediate (High School)
Dauer
45 Min.
Geschätzte Kosten
$15,00
Schritte
8
Materialien
4

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Frequently Asked Questions

What is the objective of Säure-Base-Titration mit Phenolphthalein?
Die Konzentration einer unbekannten Salzsäurelösung durch Titration mit einer standardisierten Natriumhydroxidlösung unter Verwendung von Phenolphthalein als Indikator bestimmen.
How difficult is Säure-Base-Titration mit Phenolphthalein?
This experiment is rated as Intermediate (High School). It takes approximately 45 minutes to complete.
What safety precautions are needed for Säure-Base-Titration mit Phenolphthalein?
Key safety precautions include: NaOH is corrosive — avoid skin and eye contact; HCl is corrosive — handle with care; Wear safety goggles throughout.
What materials are needed for Säure-Base-Titration mit Phenolphthalein?
The main materials required are: Hydrochloric acid (HCl), Sodium hydroxide (NaOH), Phenolphthalein indicator, Distilled water.
What results should I expect from Säure-Base-Titration mit Phenolphthalein?
The endpoint should show a clear transition from colorless to a persistent pale pink. Concordant titre values (within 0.10 mL) indicate good technique. The calculated concentration should match the expected value within experimental error.