過飽和と瞬間結晶化

酢酸ナトリウムの瞬間的な結晶形成を引き起こす

Crystallization Intermediate (High School) 35 分 ~$8.00

目的

過飽和酢酸ナトリウム溶液を調製し、瞬間的な結晶化を引き起こして準安定過飽和と発熱結晶化（ホットアイス）を実証する。

背景

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.

安全上の警告

  • 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

必要なPPE

goggles

材料

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

器具

250 mL beaker or flask Hot plate Stirring rod Thermometer

手順

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 分 Handle hot solution carefully
2

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

15 分
3

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

2 分
4

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

2 分
5

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

2 分 Crystals will be warm
6

The process is reversible — reheat to dissolve and repeat.

5 分

予想される結果

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.

後片付け

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

詳細

カテゴリ
Crystallization
難易度
Intermediate (High School)
所要時間
35 分
推定費用
$8.00
ステップ数
6
材料
2

その他の実験

サロール（サリチル酸フェニル）の結晶化 30 min ビスマス虹色結晶の育成 45 min ミョウバン結晶の育成 30 min 塩と砂の分別結晶化 35 min 安息香酸の再結晶精製 45 min 砂糖の結晶（ロックキャンディ） 25 min 硫酸銅結晶の育成 30 min

Frequently Asked Questions

What is the objective of 過飽和と瞬間結晶化?
過飽和酢酸ナトリウム溶液を調製し、瞬間的な結晶化を引き起こして準安定過飽和と発熱結晶化（ホットアイス）を実証する。
How difficult is 過飽和と瞬間結晶化?
This experiment is rated as Intermediate (High School). It takes approximately 35 minutes to complete.
What safety precautions are needed for 過飽和と瞬間結晶化?
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 過飽和と瞬間結晶化?
The main materials required are: Sodium acetate trihydrate, Distilled water.
What results should I expect from 過飽和と瞬間結晶化?
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.