Pengujian Air Sadah dengan Larutan Sabun

Membandingkan kesadahan air dengan mengukur pembentukan busa sabun

Qualitative Analysis Beginner (Middle School) 40 menit ~$6,00

Tujuan

Tentukan kesadahan relatif sampel air dengan mengukur volume larutan sabun yang diperlukan untuk menghasilkan busa yang bertahan.

Latar Belakang

Hard water contains dissolved calcium and magnesium ions (Ca²⁺, Mg²⁺) that react with soap (sodium stearate) to form an insoluble scum before lather can form. By titrating water samples with a standard soap solution and counting the number of drops needed for a persistent lather, students can rank water hardness and understand the concept of temporary vs. permanent hardness.

Peringatan Keselamatan

  • Soap solution may irritate eyes
  • Ensure stoppers are secure before shaking
  • Let boiled water cool before handling

APD yang Diperlukan

goggles lab_coat

Bahan

  • Soap solution (standard) (50 mL)
    Liquid castile soap diluted 1:10
  • Distilled water (50 mL)
    Control (soft water)
  • Tap water (50 mL)
    Unknown hardness
  • Mineral water (50 mL)
    Known mineral content
  • Calcium chloride solution (0.01M) (50 mL)
    Simulated hard water
  • Boiled tap water (50 mL)
    Temporary hardness removed

Peralatan

Stoppered test tubes or small bottles (6) Dropper pipette (calibrated) Measuring cylinder (10 mL) Marker pen

Prosedur

1

Label 6 test tubes: distilled, tap, mineral, CaCl₂, boiled tap. Add 10 mL of each water sample.

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2

Add soap solution one drop at a time to the distilled water. After each drop, stopper and shake vigorously for 10 seconds. Count drops until a lather persists for 30 seconds.

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3

Repeat Step 2 for each water sample, recording the number of drops needed for persistent lather.

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4

Compare results: rank samples from softest (fewest drops) to hardest (most drops).

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5

Compare boiled tap water to unboiled tap water. The difference indicates temporary hardness (from Ca(HCO₃)₂).

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Hasil yang Diharapkan

Distilled water requires the fewest drops of soap. CaCl₂ solution requires the most. Boiled tap water should require fewer drops than unboiled tap water, demonstrating removal of temporary hardness.

Pembersihan

Pour soapy water down the drain with running water. Rinse all test tubes and stoppers.

Detail

Kategori
Qualitative Analysis
Tingkat Kesulitan
Beginner (Middle School)
Durasi
40 menit
Perkiraan Biaya
$6,00
Langkah
5
Bahan
6

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Frequently Asked Questions

What is the objective of Pengujian Air Sadah dengan Larutan Sabun?
Tentukan kesadahan relatif sampel air dengan mengukur volume larutan sabun yang diperlukan untuk menghasilkan busa yang bertahan.
How difficult is Pengujian Air Sadah dengan Larutan Sabun?
This experiment is rated as Beginner (Middle School). It takes approximately 40 minutes to complete.
What safety precautions are needed for Pengujian Air Sadah dengan Larutan Sabun?
Key safety precautions include: Soap solution may irritate eyes; Ensure stoppers are secure before shaking; Let boiled water cool before handling.
What materials are needed for Pengujian Air Sadah dengan Larutan Sabun?
The main materials required are: Soap solution (standard), Distilled water, Tap water, Mineral water, Calcium chloride solution (0.01M).
What results should I expect from Pengujian Air Sadah dengan Larutan Sabun?
Distilled water requires the fewest drops of soap. CaCl₂ solution requires the most. Boiled tap water should require fewer drops than unboiled tap water, demonstrating removal of temporary hardness.