Радуга pH-индикаторов

Картирование изменений цвета индикаторов во всём диапазоне pH

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

Цель

Наблюдать, как разные pH-индикаторы изменяют цвет при определённых значениях pH, и понять концепцию интервала перехода индикатора.

Предпосылки

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.

Предупреждения по безопасности

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

Требуемые СИЗ

goggles lab_coat

Материалы

  • 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

Оборудование

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

Процедура

1

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

10 мин 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 мин
3

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

5 мин
4

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

5 мин
5

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

5 мин
6

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

15 мин

Ожидаемые результаты

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.

Уборка

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

Детали

Категория
Qualitative Analysis
Сложность
Beginner (Middle School)
Продолжительность
45 мин
Прим. стоимость
$8,00
Шаги
6
Материалы
6

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Frequently Asked Questions

What is the objective of Радуга pH-индикаторов?
Наблюдать, как разные pH-индикаторы изменяют цвет при определённых значениях pH, и понять концепцию интервала перехода индикатора.
How difficult is Радуга pH-индикаторов?
This experiment is rated as Beginner (Middle School). It takes approximately 45 minutes to complete.
What safety precautions are needed for Радуга pH-индикаторов?
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 Радуга pH-индикаторов?
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 Радуга pH-индикаторов?
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.