水の電気分解

水を水素と酸素に分解する

Electrochemistry Intermediate (High School) 40 分 ~$15.00

目的

電気分解により水を水素と酸素に分解し、化学量論で予測される2:1の体積比を検証する。

背景

Water electrolysis uses electrical energy to drive the non-spontaneous decomposition of water. At the cathode, water is reduced to hydrogen gas; at the anode, water is oxidized to oxygen gas. A small amount of electrolyte (sulfuric acid or sodium sulfate) is added to increase conductivity.

安全上の警告

  • Hydrogen gas is flammable — no open flames nearby
  • Do not use excessive voltage (above 12V)
  • Ensure proper ventilation

必要なPPE

goggles lab_coat

材料

  • Distilled water (500 mL)
  • Sodium sulfate (Na₂SO₄) (5 g)
    Electrolyte
  • Universal indicator (5 mL)
    Optional, to show pH changes

器具

9V battery or DC power supply Two graphite or platinum electrodes Two inverted graduated cylinders or test tubes Beaker (600 mL) Wires with alligator clips Stand and clamps

手順

1

Dissolve 5 g of sodium sulfate in 500 mL of distilled water in the beaker.

3 分
2

Fill two graduated cylinders completely with the solution and invert them over the electrodes in the beaker.

5 分
3

Connect the electrodes to the DC power supply or battery. Note which electrode is connected to positive (anode) and negative (cathode).

3 分
4

Turn on the power supply and observe gas bubbles forming at both electrodes.

2 分
5

Collect gas in the inverted cylinders for 15-20 minutes, recording the volume at each electrode every 5 minutes.

20 分 Keep flames away — hydrogen is flammable
6

Compare the volumes of gas collected. The cathode (H₂) should collect twice the volume of the anode (O₂).

3 分
7

Optionally, test the cathode gas with a lit splint (squeaky pop test for H₂) and the anode gas with a glowing splint (relights for O₂).

3 分 Use small quantities for gas tests

予想される結果

The cathode should collect approximately twice the volume of gas as the anode, confirming the 2:1 ratio of H₂ to O₂. If universal indicator is added, the solution near the cathode turns blue/purple (basic) and near the anode turns red/orange (acidic).

後片付け

Disconnect the power supply. Dispose of the solution down the drain. Rinse and dry the electrodes.

詳細

カテゴリ
Electrochemistry
難易度
Intermediate (High School)
所要時間
40 分
推定費用
$15.00
ステップ数
7
材料
3

その他の実験

ダニエル電池の製作 45 min ボルタ電池の起電力測定 60 min レモン電池 20 min 活動列の確認 30 min 濃淡電池 45 min 硫酸銅の電気分解 50 min 銅電気めっき 60 min 防錆方法の比較 30 min

Frequently Asked Questions

What is the objective of 水の電気分解?
電気分解により水を水素と酸素に分解し、化学量論で予測される2:1の体積比を検証する。
How difficult is 水の電気分解?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for 水の電気分解?
Key safety precautions include: Hydrogen gas is flammable — no open flames nearby; Do not use excessive voltage (above 12V); Ensure proper ventilation.
What materials are needed for 水の電気分解?
The main materials required are: Distilled water, Sodium sulfate (Na₂SO₄), Universal indicator.
What results should I expect from 水の電気分解?
The cathode should collect approximately twice the volume of gas as the anode, confirming the 2:1 ratio of H₂ to O₂. If universal indicator is added, the solution near the cathode turns blue/purple (basic) and near the anode turns red/orange (acidic).