pH-Indikator-Regenbogen

Kartierung der Indikatorfarbenänderungen über den gesamten pH-Bereich

Qualitative Analysis Beginner (Middle School) 45 Min. ~$8,00

Ziel

Beobachten, wie verschiedene pH-Indikatoren bei bestimmten pH-Werten die Farbe wechseln, und das Konzept des Indikator-Umschlagbereichs verstehen.

Hintergrund

pH indicators are weak acids or bases whose conjugate forms have different colors. Each indicator has a characteristic transition range where it changes color. By testing multiple indicators across a range of buffered solutions, students create a visual map of indicator behavior that reinforces concepts of acid-base equilibrium and the Henderson-Hasselbalch equation.

Sicherheitswarnungen

  • Indicators can stain skin and clothing
  • Extreme pH solutions (pH 1, 14) are corrosive
  • Avoid mixing different buffer solutions

Erforderliche PSA

goggles lab_coat

Materialien

  • Buffer solutions (pH 1–14) (5 mL each)
    Pre-prepared set
  • Methyl orange indicator (5 mL)
    pH 3.1–4.4 range
  • Bromothymol blue indicator (5 mL)
    pH 6.0–7.6 range
  • Phenolphthalein indicator (5 mL)
    pH 8.2–10.0 range
  • Universal indicator (5 mL)
    Full pH range
  • Litmus solution (red and blue) (5 mL each)
    Simple acid/base test

Ausrüstung

Spot plate or microwell plate Dropper pipettes (one per indicator) pH meter or pH paper White background paper

Durchführung

1

Arrange the spot plate and add 10 drops of each buffer solution (pH 1 through 14) across each row.

10 Min. Handle pH 1 and 14 solutions carefully
2

Add 2 drops of methyl orange to the first row of buffer solutions. Record the color at each pH.

5 Min.
3

Add 2 drops of bromothymol blue to the second row. Record the color at each pH.

5 Min.
4

Add 2 drops of phenolphthalein to the third row. Record the color at each pH.

5 Min.
5

Add 2 drops of universal indicator to the fourth row. Observe the full rainbow of colors.

5 Min.
6

Create a color chart recording each indicator's color at every pH level. Identify each indicator's transition range.

15 Min.

Erwartete Ergebnisse

Methyl orange: red (acidic) to yellow (basic) around pH 3–4. Bromothymol blue: yellow to blue around pH 6–7.6. Phenolphthalein: colorless to pink around pH 8–10. Universal indicator: red through violet across the full pH range.

Aufräumen

Pour solutions into the appropriate waste container (acid or base). Rinse spot plates thoroughly with distilled water.

Details

Kategorie
Qualitative Analysis
Schwierigkeit
Beginner (Middle School)
Dauer
45 Min.
Geschätzte Kosten
$8,00
Schritte
6
Materialien
6

Weitere Experimente

Beilstein-Test auf Halogene 25 min Borax-Perlentest auf Metallionen 45 min Chromatographie von Pflanzenpigmenten 60 min Flammen-Emissionsspektroskopie 60 min Identifikationsaufgabe für unbekannte Substanzen 75 min Kationenidentifikation durch Fällung 90 min Stärke-Iod-Test auf Kohlenhydrate 30 min Tests zur Anionenidentifikation 60 min Wasserhärtetest mit Seifenlösung 40 min

Frequently Asked Questions

What is the objective of pH-Indikator-Regenbogen?
Beobachten, wie verschiedene pH-Indikatoren bei bestimmten pH-Werten die Farbe wechseln, und das Konzept des Indikator-Umschlagbereichs verstehen.
How difficult is pH-Indikator-Regenbogen?
This experiment is rated as Beginner (Middle School). It takes approximately 45 minutes to complete.
What safety precautions are needed for pH-Indikator-Regenbogen?
Key safety precautions include: Indicators can stain skin and clothing; Extreme pH solutions (pH 1, 14) are corrosive; Avoid mixing different buffer solutions.
What materials are needed for pH-Indikator-Regenbogen?
The main materials required are: Buffer solutions (pH 1–14), Methyl orange indicator, Bromothymol blue indicator, Phenolphthalein indicator, Universal indicator.
What results should I expect from pH-Indikator-Regenbogen?
Methyl orange: red (acidic) to yellow (basic) around pH 3–4. Bromothymol blue: yellow to blue around pH 6–7.6. Phenolphthalein: colorless to pink around pH 8–10. Universal indicator: red through violet across the full pH range.