침전 적정(모어법)

질산은을 이용한 염화물 농도 결정하기

Titrations Advanced (University) 45 분 ~$20.00

목표

질산은을 적정액, 크롬산칼륨을 지시약으로 사용하는 모어법으로 용액 중 염화 이온 농도를 결정한다.

배경

In the Mohr method, silver nitrate reacts with chloride ions to form white silver chloride precipitate. When all chloride is consumed, the first excess silver reacts with the chromate indicator to form brick-red silver chromate, signaling the endpoint. This method works at near-neutral pH.

안전 경고

  • Silver nitrate stains skin and clothing permanently
  • Potassium chromate is toxic and a suspected carcinogen — handle with extreme care
  • Wear nitrile gloves and safety goggles
  • Dispose of silver and chromate waste in designated containers

필수 개인 보호 장비

goggles gloves lab_coat

재료

  • Sodium chloride solution (100 mL)
    Unknown concentration
  • Silver nitrate (AgNO₃) (100 mL)
    0.1M standardized
  • Potassium chromate (K₂CrO₄) (10 mL)
    5% indicator solution
  • Distilled water (200 mL)

장비

50 mL burette Burette stand and clamp 250 mL Erlenmeyer flask 25 mL pipette White tile

실험 절차

1

Pipette 25.0 mL of the chloride solution into the Erlenmeyer flask.

2 분
2

Add 1 mL of 5% potassium chromate indicator. The solution turns pale yellow.

1 분 Chromate is toxic — use minimal amount
3

Fill the burette with 0.1M AgNO₃. Record the initial volume.

3 분 AgNO₃ stains permanently
4

Titrate while swirling vigorously. A white precipitate of AgCl forms.

10 분
5

Near the endpoint, the precipitate becomes more curd-like. Add AgNO₃ drop by drop until a permanent brick-red color of Ag₂CrO₄ appears.

5 분
6

Record the volume. Repeat for concordant results.

15 분
7

Calculate chloride concentration: C(Cl⁻) = C(Ag+) x V(AgNO₃) / V(sample).

5 분

예상 결과

The endpoint is marked by the first permanent appearance of a brick-red color due to Ag₂CrO₄ formation. This color should persist for at least 30 seconds after swirling.

정리

Collect all silver-containing waste in the designated heavy metal waste container. Collect chromate waste separately. Never dispose down the drain. Wash hands thoroughly.

세부 정보

카테고리
Titrations
난이도
Advanced (University)
소요 시간
45 분
예상 비용
$20.00
단계
7
재료
4

더 많은 실험

페놀프탈레인을 이용한 산염기 적정 45 min 과망간산칼륨 산화환원 적정 50 min 표백제의 아이오딘 적정 50 min 전도도 적정 50 min 제산제 정제의 역적정 60 min 메틸 오렌지를 이용한 산염기 적정 40 min 이중 지시약을 이용한 탄산염-중탄산염 혼합물 적정 55 min 아이오딘을 이용한 비타민 C 적정 40 min EDTA 착화 적정을 이용한 물 경도 측정 45 min pH 적정 곡선 50 min

Frequently Asked Questions

What is the objective of 침전 적정(모어법)?
질산은을 적정액, 크롬산칼륨을 지시약으로 사용하는 모어법으로 용액 중 염화 이온 농도를 결정한다.
How difficult is 침전 적정(모어법)?
This experiment is rated as Advanced (University). It takes approximately 45 minutes to complete.
What safety precautions are needed for 침전 적정(모어법)?
Key safety precautions include: Silver nitrate stains skin and clothing permanently; Potassium chromate is toxic and a suspected carcinogen — handle with extreme care; Wear nitrile gloves and safety goggles.
What materials are needed for 침전 적정(모어법)?
The main materials required are: Sodium chloride solution, Silver nitrate (AgNO₃), Potassium chromate (K₂CrO₄), Distilled water.
What results should I expect from 침전 적정(모어법)?
The endpoint is marked by the first permanent appearance of a brick-red color due to Ag₂CrO₄ formation. This color should persist for at least 30 seconds after swirling.