Preparation of a simplified standard hydrogen electrode and measurement of some standard potentials with Cobra SMARTsense

Principle

A relative electrical potential can be assigned to each metal and other redox pairs if it is combined with a constant reference electrode in a galvanic cell. The so-called standard hydrogen electrode (SHE) was defined as the international reference electrode for this purpose. In the present experiment, a simplified form of this electrode is constructed and the redox potentials of various metals are determined experimentally.

For this purpose, a platinum electrode is charged with hydrogen gas by electrolysis of a sulphuric acid solution. This hydrogen electrode is then successively connected to four half cells of different metals to form galvanic cells. The resulting voltages are measured and classified in a voltage series according to their magnitude and sign. The aim of the experiment is to illustrate the principle and structure of the standard hydrogen electrode and to deepen the understanding of electrochemical potentials.

Tasks

1. A platinum electrode is actively charged with hydrogen gas by electrolyzing a sulphuric acid solution.
2. The charged platinum electrode is then combined with four half cells of different metals to form galvanic cells.
3. The resulting cell voltages are measured and arranged in a voltage series according to their magnitude and sign.

Learning objective

In the course of the experiment, the students will produce a simplified standard hydrogen electrode so that an understanding of its functional principle and structure is deepened. The term "standard potential" is also covered.

Benefits

• The experiment is part of a complete set that covers all important curricular topics in electrochemistry.
• Quick and easy experiment preparation (experiment instructions and risk assessment available).