コーヒーカップ熱量測定

簡易熱量計を使って中和エンタルピーを測定する

Thermochemistry Intermediate (High School) 40 分 ~$8.00

目的

ポリスチレンカップ熱量計を用いてHClとNaOHの中和エンタルピーを決定する。

背景

A polystyrene cup makes an inexpensive but effective calorimeter because it has low thermal conductivity. By mixing known volumes of acid and base and measuring the temperature change, the enthalpy of neutralization can be calculated. The accepted value for strong acid-strong base neutralization is -57.1 kJ/mol.

安全上の警告

  • HCl and NaOH are corrosive
  • Wear safety goggles
  • The mixture will get hot

必要なPPE

goggles gloves lab_coat

材料

  • Hydrochloric acid (HCl) (50 mL)
    1M
  • Sodium hydroxide (NaOH) (50 mL)
    1M
  • Distilled water (100 mL)
    For calibration

器具

Two polystyrene (Styrofoam) cups (nested) Cardboard lid with hole Thermometer (0.1°C resolution) Graduated cylinder (50 mL) Stopwatch

手順

1

Measure 50 mL of 1M HCl and pour into the nested polystyrene cups. Record the initial temperature every 30 seconds for 3 minutes.

5 分 HCl is corrosive
2

Measure 50 mL of 1M NaOH in a separate container. Record its temperature.

2 分 NaOH is corrosive
3

Quickly pour the NaOH into the HCl, stir gently, and replace the lid with thermometer.

1 分 Exothermic reaction
4

Record the temperature every 30 seconds for 5 minutes. Note the maximum temperature.

5 分
5

Plot temperature vs time. Extrapolate the cooling curve back to the mixing time to find the corrected maximum temperature.

5 分
6

Calculate ΔT, then q = mcΔT (assume c = 4.18 J/g°C, mass = 100 g). Calculate ΔH per mole of water formed.

8 分

予想される結果

Temperature should rise by approximately 6-7°C. Calculated ΔH should be approximately -50 to -57 kJ/mol (accepted: -57.1 kJ/mol). Losses to the calorimeter walls typically give lower values.

後片付け

The neutralized solution is safe to pour down the drain. Rinse and dry the calorimeter cups for reuse.

詳細

カテゴリ
Thermochemistry
難易度
Intermediate (High School)
所要時間
40 分
推定費用
$8.00
ステップ数
6
材料
3

その他の実験

コールドパックの化学 20 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 コーヒーカップ熱量測定?
ポリスチレンカップ熱量計を用いてHClとNaOHの中和エンタルピーを決定する。
How difficult is コーヒーカップ熱量測定?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for コーヒーカップ熱量測定?
Key safety precautions include: HCl and NaOH are corrosive; Wear safety goggles; The mixture will get hot.
What materials are needed for コーヒーカップ熱量測定?
The main materials required are: Hydrochloric acid (HCl), Sodium hydroxide (NaOH), Distilled water.
What results should I expect from コーヒーカップ熱量測定?
Temperature should rise by approximately 6-7°C. Calculated ΔH should be approximately -50 to -57 kJ/mol (accepted: -57.1 kJ/mol). Losses to the calorimeter walls typically give lower values.