Электролиз воды

Разложение воды на водород и кислород

Electrochemistry Intermediate (High School) 40 мин ~$15,00

Цель

Разложить воду электролизом на водород и кислород и подтвердить объёмное соотношение 2:1, предсказанное стехиометрией.

Предпосылки

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.

Предупреждения по безопасности

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

Требуемые СИЗ

goggles lab_coat

Материалы

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

Оборудование

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

Процедура

1

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

3 мин
2

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

5 мин
3

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

3 мин
4

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

2 мин
5

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

20 мин 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 мин
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 мин Use small quantities for gas tests

Ожидаемые результаты

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).

Уборка

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

Детали

Категория
Electrochemistry
Сложность
Intermediate (High School)
Продолжительность
40 мин
Прим. стоимость
$15,00
Шаги
7
Материалы
3

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Frequently Asked Questions

What is the objective of Электролиз воды?
Разложить воду электролизом на водород и кислород и подтвердить объёмное соотношение 2:1, предсказанное стехиометрией.
How difficult is Электролиз воды?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for Электролиз воды?
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 Электролиз воды?
The main materials required are: Distilled water, Sodium sulfate (Na₂SO₄), Universal indicator.
What results should I expect from Электролиз воды?
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).