침전에 의한 양이온 확인

선택적 시약을 이용한 I~V족 양이온의 계통적 분리

Qualitative Analysis Intermediate (High School) 90 분 ~$12.00

목표

그룹 시약을 이용한 고전적 정성 분석 방식으로 용액 속의 미지 양이온을 확인한다.

배경

Classical qualitative analysis divides cations into five analytical groups based on their solubility with specific reagents. Group I cations (Ag⁺, Pb²⁺, Hg₂²⁺) precipitate with dilute HCl. Group II (Cu²⁺, Bi³⁺, Cd²⁺) precipitate with H₂S in acidic solution. This systematic approach was developed in the 19th century and remains a cornerstone of analytical chemistry education.

안전 경고

  • H₂S is toxic — work in fume hood at all times
  • Wear gloves when handling concentrated reagents
  • Never mix reagents without understanding the expected reaction
  • Dispose of heavy metal solutions in designated waste containers

필수 개인 보호 장비

goggles gloves lab_coat

재료

  • Unknown cation solution (10 mL)
    Prepared by instructor
  • Dilute HCl (2M) (20 mL)
    Group I reagent
  • H₂S solution or thioacetamide (10 mL)
    Group II reagent
  • NH₄OH (6M) (10 mL)
    Group III reagent
  • (NH₄)₂CO₃ solution (10 mL)
    Group IV reagent
  • NaOH (6M) (10 mL)
    Confirmation tests
  • Distilled water (100 mL)
    For washing precipitates

장비

Test tubes (10) Centrifuge Hot water bath Dropper pipettes Test tube rack Wash bottle

실험 절차

1

Add 1 mL of 2M HCl to 5 mL of unknown solution. If a precipitate forms, centrifuge and separate the supernatant from the Group I precipitate.

10 분
2

Test the Group I precipitate: wash with hot water (PbCl₂ dissolves), then add NH₄OH (AgCl dissolves forming [Ag(NH₃)₂]⁺).

10 분
3

To the supernatant from Step 1, add thioacetamide or H₂S in acidic conditions. Centrifuge any Group II precipitate.

15 분 Use fume hood for H₂S
4

Make the supernatant basic with NH₄OH and add (NH₄)₂S. Centrifuge any Group III precipitate (Fe, Al, Cr hydroxides).

15 분
5

To the remaining solution, add (NH₄)₂CO₃. Group IV cations (Ca²⁺, Ba²⁺, Sr²⁺) precipitate as carbonates.

10 분
6

The remaining solution contains Group V cations (Na⁺, K⁺, NH₄⁺). Confirm with flame tests or specific reagent tests.

15 분
7

Perform confirmation tests on each group precipitate and record your findings.

15 분

예상 결과

Each analytical group should produce characteristic precipitates with specific colors. Confirmation tests (flame tests, specific reagents) identify the individual cations present in the unknown solution.

정리

Collect all heavy metal waste in labeled containers. Rinse test tubes three times with distilled water. Clean centrifuge tubes thoroughly.

세부 정보

카테고리
Qualitative Analysis
난이도
Intermediate (High School)
소요 시간
90 분
예상 비용
$12.00
단계
7
재료
7

더 많은 실험

탄수화물의 아이오딘-전분 시험 30 min 할로겐에 대한 베이슈타인 시험 25 min 음이온 확인 시험 60 min 비누 용액으로 경수 시험 40 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 침전에 의한 양이온 확인?
그룹 시약을 이용한 고전적 정성 분석 방식으로 용액 속의 미지 양이온을 확인한다.
How difficult is 침전에 의한 양이온 확인?
This experiment is rated as Intermediate (High School). It takes approximately 90 minutes to complete.
What safety precautions are needed for 침전에 의한 양이온 확인?
Key safety precautions include: H₂S is toxic — work in fume hood at all times; Wear gloves when handling concentrated reagents; Never mix reagents without understanding the expected reaction.
What materials are needed for 침전에 의한 양이온 확인?
The main materials required are: Unknown cation solution, Dilute HCl (2M), H₂S solution or thioacetamide, NH₄OH (6M), (NH₄)₂CO₃ solution.
What results should I expect from 침전에 의한 양이온 확인?
Each analytical group should produce characteristic precipitates with specific colors. Confirmation tests (flame tests, specific reagents) identify the individual cations present in the unknown solution.