コールドパックの化学

硝酸アンモニウムの吸熱溶解を調べる

Thermochemistry Beginner (Middle School) 20 分 ~$6.00

目的

硝酸アンモニウムが水に溶けるときの温度変化を測定し、インスタント冷却パックに使われる吸熱溶解プロセスを実証する。

背景

Ammonium nitrate dissolves endothermically in water, absorbing heat from the surroundings and causing a significant temperature drop. This principle is used in commercial instant cold packs for first aid. The dissolution has ΔH = +25.7 kJ/mol.

安全上の警告

  • Ammonium nitrate is an oxidizer — keep away from organic materials and heat
  • Do not mix with anything other than water for this experiment
  • Wear goggles

必要なPPE

goggles

材料

  • Ammonium nitrate (NH₄NO₃) (30 g)
    Or from a commercial cold pack
  • Distilled water (100 mL)
    Room temperature

器具

Polystyrene cup calorimeter Thermometer Stirring rod Analytical balance

手順

1

Add 100 mL of distilled water to the polystyrene cup calorimeter. Record the initial temperature.

3 分
2

Weigh 30 g of ammonium nitrate.

2 分 Ammonium nitrate is an oxidizer
3

Add the ammonium nitrate to the water. Stir gently to dissolve.

3 分
4

Record the temperature every 30 seconds as it drops. Note the minimum temperature.

5 分
5

Feel the outside of the cup — it should feel cold.

1 分
6

Calculate ΔH of dissolution per mole: q = mcΔT, n = mass/M(NH₄NO₃), ΔH = q/n.

5 分

予想される結果

Temperature should drop 15-20°C. 30 g NH₄NO₃ = 0.375 mol. q = 100 × 4.18 × ΔT. Calculated ΔH should be approximately +25 kJ/mol (±15%).

後片付け

The ammonium nitrate solution is safe to dispose down the drain (dilute). Rinse the calorimeter.

詳細

カテゴリ
Thermochemistry
難易度
Beginner (Middle School)
所要時間
20 分
推定費用
$6.00
ステップ数
6
材料
2

その他の実験

コーヒーカップ熱量測定 40 min ヘスの法則の検証 60 min マグネシウムの燃焼熱 50 min 吸熱反応のデモンストレーション 20 min 氷の融解エンタルピー 25 min 溶解は常に発熱ではない 25 min 爆弾熱量測定シミュレーション 45 min 酢酸ナトリウムの発熱結晶化 30 min 金属の比熱容量 40 min

Frequently Asked Questions

What is the objective of コールドパックの化学?
硝酸アンモニウムが水に溶けるときの温度変化を測定し、インスタント冷却パックに使われる吸熱溶解プロセスを実証する。
How difficult is コールドパックの化学?
This experiment is rated as Beginner (Middle School). It takes approximately 20 minutes to complete.
What safety precautions are needed for コールドパックの化学?
Key safety precautions include: Ammonium nitrate is an oxidizer — keep away from organic materials and heat; Do not mix with anything other than water for this experiment; Wear goggles.
What materials are needed for コールドパックの化学?
The main materials required are: Ammonium nitrate (NH₄NO₃), Distilled water.
What results should I expect from コールドパックの化学?
Temperature should drop 15-20°C. 30 g NH₄NO₃ = 0.375 mol. q = 100 × 4.18 × ΔT. Calculated ΔH should be approximately +25 kJ/mol (±15%).