비누 용액으로 경수 시험

비누 거품 형성으로 물의 경도 비교하기

Qualitative Analysis Beginner (Middle School) 40 분 ~$6.00

목표

지속적인 거품이 발생하는 데 필요한 비누 용액의 양을 측정하여 물 시료의 상대적 경도를 결정한다.

배경

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.

안전 경고

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

필수 개인 보호 장비

goggles lab_coat

재료

  • 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

장비

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

실험 절차

1

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

5 분
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.

5 분
3

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

20 분
4

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

5 분
5

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

5 분

예상 결과

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.

정리

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

세부 정보

카테고리
Qualitative Analysis
난이도
Beginner (Middle School)
소요 시간
40 분
예상 비용
$6.00
단계
5
재료
6

더 많은 실험

탄수화물의 아이오딘-전분 시험 30 min 할로겐에 대한 베이슈타인 시험 25 min 음이온 확인 시험 60 min 침전에 의한 양이온 확인 90 min 식물 색소의 크로마토그래피 60 min 금속 이온에 대한 붕사 구슬 시험 45 min 미지 물질 확인 도전 75 min 불꽃 발광 분광 분석 60 min pH 지시약 무지개 45 min

Frequently Asked Questions

What is the objective of 비누 용액으로 경수 시험?
지속적인 거품이 발생하는 데 필요한 비누 용액의 양을 측정하여 물 시료의 상대적 경도를 결정한다.
How difficult is 비누 용액으로 경수 시험?
This experiment is rated as Beginner (Middle School). It takes approximately 40 minutes to complete.
What safety precautions are needed for 비누 용액으로 경수 시험?
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 비누 용액으로 경수 시험?
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 비누 용액으로 경수 시험?
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.