과포화와 순간 결정화

아세트산나트륨의 순간 결정 형성 유도하기

Crystallization Intermediate (High School) 35 분 ~$8.00

목표

과포화 아세트산나트륨 용액을 만들고 순간 결정화를 유도하여 준안정 과포화와 발열 결정화(핫 아이스)를 실증한다.

배경

Sodium acetate trihydrate can form extremely supersaturated solutions that remain liquid until disturbed. Adding a single seed crystal or scratching the container wall triggers rapid crystallization throughout the solution, releasing heat (exothermic). The resulting solid resembles ice but is warm to the touch.

안전 경고

  • The solution gets hot when it crystallizes — handle with care
  • Sodium acetate is generally safe but avoid ingestion
  • Use heat-resistant gloves when handling hot solution

필수 개인 보호 장비

goggles

재료

  • Sodium acetate trihydrate (100 g)
    Or make from vinegar + baking soda
  • Distilled water (10 mL)
    Minimal amount

장비

250 mL beaker or flask Hot plate Stirring rod Thermometer

실험 절차

1

Add 100 g sodium acetate trihydrate and 10 mL water to the beaker. Heat while stirring until all crystals dissolve (about 70°C).

8 분 Handle hot solution carefully
2

Remove from heat and allow to cool to room temperature undisturbed. Do not shake or add anything.

15 분
3

Once cooled, the solution should remain liquid despite being supersaturated. Measure the temperature.

2 분
4

Drop a single small crystal of sodium acetate into the solution and observe the rapid crystallization wave.

2 분
5

Immediately measure the temperature of the newly formed crystals. Note the temperature increase (exothermic).

2 분 Crystals will be warm
6

The process is reversible — reheat to dissolve and repeat.

5 분

예상 결과

When triggered, crystallization should sweep through the solution in seconds, forming a solid mass of warm crystals (hence "hot ice"). The temperature typically rises 10-20°C above room temperature. This is the principle behind reusable hand warmers.

정리

Sodium acetate is reusable. Simply reheat to dissolve. Can be disposed down the drain. Rinse equipment.

세부 정보

카테고리
Crystallization
난이도
Intermediate (High School)
소요 시간
35 분
예상 비용
$8.00
단계
6
재료
2

더 많은 실험

비스무트 무지개빛 결정 키우기 45 min 안식향산 재결정 정제 45 min 황산구리 결정 키우기 30 min 소금과 모래의 분별 결정화 35 min 명반 결정 키우기 30 min 설탕 결정(락캔디) 25 min 살롤(살리실산페닐) 결정화 30 min

Frequently Asked Questions

What is the objective of 과포화와 순간 결정화?
과포화 아세트산나트륨 용액을 만들고 순간 결정화를 유도하여 준안정 과포화와 발열 결정화(핫 아이스)를 실증한다.
How difficult is 과포화와 순간 결정화?
This experiment is rated as Intermediate (High School). It takes approximately 35 minutes to complete.
What safety precautions are needed for 과포화와 순간 결정화?
Key safety precautions include: The solution gets hot when it crystallizes — handle with care; Sodium acetate is generally safe but avoid ingestion; Use heat-resistant gloves when handling hot solution.
What materials are needed for 과포화와 순간 결정화?
The main materials required are: Sodium acetate trihydrate, Distilled water.
What results should I expect from 과포화와 순간 결정화?
When triggered, crystallization should sweep through the solution in seconds, forming a solid mass of warm crystals (hence "hot ice"). The temperature typically rises 10-20°C above room temperature. This is the principle behind reusable hand warmers.