水的电解

将水分解为氢气和氧气

Electrochemistry Intermediate (High School) 40 分钟 ~$15.00

目标

通过电解将水分解为氢气和氧气，验证化学计量学预测的2:1体积比。

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.

安全警告

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

所需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

设备

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

步骤

1

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

3 分钟
2

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

5 分钟
3

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

3 分钟
4

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

2 分钟
5

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

20 分钟 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 分钟
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 分钟 Use small quantities for gas tests

预期结果

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).

清理

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

详情

类别
Electrochemistry
难度
Intermediate (High School)
时长
40 分钟
预估费用
$15.00
步骤数
7
材料
3

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Frequently Asked Questions

What is the objective of 水的电解?
通过电解将水分解为氢气和氧气，验证化学计量学预测的2:1体积比。
How difficult is 水的电解?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for 水的电解?
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 水的电解?
The main materials required are: Distilled water, Sodium sulfate (Na₂SO₄), Universal indicator.
What results should I expect from 水的电解?
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).