미지 물질 확인 도전

물리적·화학적 성질로 신비의 분말 확인하기

Qualitative Analysis Intermediate (High School) 75 분 ~$10.00

목표

다양한 정성 시험을 적용하여 미지 백색 분말을 확인하고, 체계적인 분석 사고력을 기른다.

배경

This integrative experiment challenges students to identify unknown white powders from a set of possibilities (NaCl, NaHCO₃, CaCO₃, cornstarch, sugar, baking powder) using a battery of physical and chemical tests. Students must design their own testing sequence, demonstrating understanding of solubility, acid reactivity, flame tests, and indicator tests.

안전 경고

  • Do not taste any unknown samples
  • Wear goggles when heating or adding acid to unknowns
  • Some unknowns may react vigorously with acid

필수 개인 보호 장비

goggles gloves lab_coat

재료

  • Unknown powders (3–5 samples) (2 g each)
    Labeled A, B, C, etc.
  • Dilute HCl (1M) (10 mL)
    For acid reactivity test
  • Distilled water (100 mL)
    For solubility test
  • Iodine solution (5 mL)
    Starch test
  • Universal indicator (5 mL)
    pH test
  • Cobalt chloride paper (5 strips)
    Water of crystallization test

장비

Test tubes (10) Bunsen burner Nichrome wire loop Spatula Magnifying glass Evaporating dish

실험 절차

1

Observe each unknown's physical appearance under magnifying glass: crystal shape, texture, color. Record observations.

10 분
2

Solubility test: Add 0.5 g of each unknown to 5 mL distilled water. Stir and observe if it dissolves, partially dissolves, or is insoluble.

10 분
3

pH test: Add 2 drops of universal indicator to the dissolved/suspended samples. Record the pH.

5 분
4

Acid reactivity: Add 5 drops of dilute HCl to a small amount of each dry unknown. Record any effervescence (CO₂ evolution).

10 분
5

Iodine test: Add 2 drops of iodine solution to each unknown dissolved in water. Record color change.

5 분
6

Flame test: Using a clean nichrome wire, test each unknown in the Bunsen burner flame.

15 분 Keep face away from flame
7

Heat test: Gently heat a small amount of each unknown in an evaporating dish. Observe melting, charring, or gas evolution.

10 분 Use tongs to handle hot dish
8

Compile all results and cross-reference to identify each unknown. Write your reasoning.

10 분

예상 결과

NaCl: soluble, neutral pH, no acid reaction, yellow flame. NaHCO₃: soluble, basic pH, effervesces with acid. CaCO₃: insoluble, effervesces with acid, orange-red flame. Cornstarch: insoluble, positive iodine test. Sugar: soluble, chars on heating.

정리

Dispose of acid-reacted solutions in waste container. Clean all test tubes and glassware. Return unused unknown samples.

세부 정보

카테고리
Qualitative Analysis
난이도
Intermediate (High School)
소요 시간
75 분
예상 비용
$10.00
단계
8
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 비누 용액으로 경수 시험 40 min 식물 색소의 크로마토그래피 60 min 금속 이온에 대한 붕사 구슬 시험 45 min 불꽃 발광 분광 분석 60 min pH 지시약 무지개 45 min

자주 묻는 질문

What is the objective of 미지 물질 확인 도전?
다양한 정성 시험을 적용하여 미지 백색 분말을 확인하고, 체계적인 분석 사고력을 기른다.
How difficult is 미지 물질 확인 도전?
This experiment is rated as Intermediate (High School). It takes approximately 75 minutes to complete.
What safety precautions are needed for 미지 물질 확인 도전?
Key safety precautions include: Do not taste any unknown samples; Wear goggles when heating or adding acid to unknowns; Some unknowns may react vigorously with acid.
What materials are needed for 미지 물질 확인 도전?
The main materials required are: Unknown powders (3–5 samples), Dilute HCl (1M), Distilled water, Iodine solution, Universal indicator.
What results should I expect from 미지 물질 확인 도전?
NaCl: soluble, neutral pH, no acid reaction, yellow flame. NaHCO₃: soluble, basic pH, effervesces with acid. CaCO₃: insoluble, effervesces with acid, orange-red flame. Cornstarch: insoluble, positive iodine test. Sugar: soluble, chars on heating.