瞬間凍結：過冷却水

過冷却水の瞬間的な結晶化を引き起こす

Classroom Demonstrations Beginner (Middle School) 120 分 ~$3.00

目的

精製水を凍結せずに0°C以下に冷却して過冷却を実証し、瞬間的な結晶化を引き起こす。

背景

Pure water can be cooled below its freezing point (0°C) without solidifying if there are no nucleation sites for ice crystals to form. This metastable state, called supercooling, can persist down to about −40°C for very pure water. When a supercooled sample is disturbed (tapped, shaken, or a small ice crystal is added), crystallization cascades through the entire sample in seconds, creating a dramatic visual effect.

安全上の警告

  • Handle glass thermometers with care
  • Do not use glass bottles — they may shatter if water freezes and expands
  • Supercooled water will freeze instantly if disturbed — handle very gently

必要なPPE

goggles

材料

  • Purified water (distilled or deionized) (500 mL)
    Must be very pure
  • Clean plastic bottles (5)
    New, unopened, smooth interior
  • Small ice crystal (1)
    Nucleation seed
  • Thermometer (−20 to 10°C) (1)

器具

Freezer (set to −8 to −10°C) Bowl Timer

手順

1

Place 5 sealed bottles of purified water in the freezer, undisturbed. Set a timer for 90 minutes (adjust based on freezer temperature).

90 分 Do not disturb the bottles
2

Very carefully remove one bottle. If it is still liquid and the temperature reads below 0°C, it is supercooled.

5 分 Handle extremely gently
3

Method 1 (Impact nucleation): Sharply tap the bottle on a table. Watch ice crystals propagate through the liquid.

2 分
4

Method 2 (Seed crystal): Carefully open a second supercooled bottle and drop a small ice chip in. Watch instant freezing from the crystal seed.

3 分
5

Method 3 (Pour): Slowly pour supercooled water onto an ice cube in a bowl. Watch an ice tower build up.

5 分
6

Discuss nucleation, supercooling, and phase transitions. Explain why purity and smooth container walls are essential.

15 分

予想される結果

The water remains liquid below 0°C until disturbed. Upon nucleation, ice crystals propagate visibly through the bottle in 2–5 seconds. Pouring onto an ice cube creates a growing column of ice.

後片付け

Thaw any frozen bottles. No chemical waste. Return thermometer to storage.

詳細

カテゴリ
Classroom Demonstrations
難易度
Beginner (Middle School)
所要時間
120 分
推定費用
$3.00
ステップ数
6
材料
4

その他の実験

テルミット反応 30 min ドライアイス中でのマグネシウムの燃焼 25 min ナトリウムと水の反応 25 min ヨウ素時計反応 45 min ルミノールによる化学発光 30 min 密度カラム虹 30 min 振動するブリッグス-ラウシャー反応 40 min 消えるビーカー（屈折率マッチング） 15 min 象の歯磨き粉 20 min 非ニュートン流体：ウブレック 20 min

Frequently Asked Questions

What is the objective of 瞬間凍結：過冷却水?
精製水を凍結せずに0°C以下に冷却して過冷却を実証し、瞬間的な結晶化を引き起こす。
How difficult is 瞬間凍結：過冷却水?
This experiment is rated as Beginner (Middle School). It takes approximately 120 minutes to complete.
What safety precautions are needed for 瞬間凍結：過冷却水?
Key safety precautions include: Handle glass thermometers with care; Do not use glass bottles — they may shatter if water freezes and expands; Supercooled water will freeze instantly if disturbed — handle very gently.
What materials are needed for 瞬間凍結：過冷却水?
The main materials required are: Purified water (distilled or deionized), Clean plastic bottles, Small ice crystal, Thermometer (−20 to 10°C).
What results should I expect from 瞬間凍結：過冷却水?
The water remains liquid below 0°C until disturbed. Upon nucleation, ice crystals propagate visibly through the bottle in 2–5 seconds. Pouring onto an ice cube creates a growing column of ice.