Problem 43 - Chemistry: An Atoms-Focused Approach

Question

A Reference Point: The Standard Hydrogen Electrode What is the function of platinum in the standard hydrogen electrode?

Step-by-Step Solution

Answer

Answer: The main functions of platinum in the standard hydrogen electrode are: 1. It provides a chemically inert and stable surface for the hydrogen electrode reaction. 2. It offers a large surface area for the reaction to occur, ensuring accurate reference potential. 3. It has a high electrical conductivity, allowing for precise measurement of electrode potentials.

Step 1: Introduction to the Standard Hydrogen Electrode

The Standard Hydrogen Electrode (SHE) is an electrode that serves as a reference point for measuring electrode potentials of other electrodes. It is set to 0 volts at all temperatures. The standard hydrogen electrode consists of a platinum electrode in contact with a solution of HCl (generally 1.0 M), and hydrogen gas is bubbled through the solution at a pressure of 1 atm.

Step 2: Purpose of Platinum in the Standard Hydrogen Electrode

Platinum serves multiple functions in the standard hydrogen electrode: 1. Platinum is a chemically inert and stable metal. It does not react with the components of the SHE, ensuring that the measurements taken are not influenced by other reactions, making it suitable for use as a reference electrode. 2. Platinum provides a large surface area for the hydrogen electrode reaction (oxidation and reduction) to occur. This ensures that any potential measured can be assumed to arise solely from the hydrogen reaction, thus providing a reference potential for other electrochemical reactions. 3. Platinum has high electrical conductivity, allowing for accurate measurement of electrode potentials. Overall, platinum is essential in the SHE's function as it provides a stable, inert surface to facilitate the hydrogen electrode reaction and allows for accurate measurement of electrode potentials.

Key Concepts

Platinum Electrode

In the world of electrochemistry, the platinum electrode plays a crucial role in the Standard Hydrogen Electrode (SHE). Platinum is chosen because it is chemically inert. This means that it does not participate in unwanted chemical reactions that might otherwise alter the results, ensuring accurate measurements.

Additionally, platinum has a remarkable ability to provide a large surface area for the hydrogen reactions. This large surface ensures that reactions of interest occur efficiently, without interference from other substances.

Furthermore, platinum's high electrical conductivity is essential. It allows easy transfer of electrons which is critical for accurate potential measurements.

• Inertness of platinum prevents unwanted side reactions.
• Large surface area aids in reaction efficiency.
• High conductivity ensures precise measurements.

Electrode Potential

Electrode potential refers to the voltage between an electrode and a reference point. In electrochemistry, we use the electrode potential to determine how easily electrons can be gained or lost. The Standard Hydrogen Electrode, with its assigned potential of 0 volts, serves as this reference point.

Using a standard reference like SHE helps scientists to compare and measure the potential of other electrodes accurately, ensuring consistent communication when discussing electrochemical cells.

• Potential difference is measured between SHE and another electrode.
• Helps in comparing different electrode reactions.
• SHE provides a consistent reference of 0 volts.

Hydrogen Reaction

In the Standard Hydrogen Electrode, the primary reactions involve hydrogen gas ( H_2 ). It can be oxidized to form protons, or reduced back from these protons to hydrogen gas. These reactions are central to the hydrogen electrode's role as a standard.

In simple terms, the reaction can be described as the interchange of hydrogen ion ( H^+ ) and hydrogen gas ( H_2 ), providing a reference potential for all redox reactions.

• H_2 (gas) ↔ 2H^+ (aqueous) + 2e^- (reaction depicting oxidation and reduction).
• Acts as a benchmark for other electrode reactions.
• The balance between oxidation and reduction is crucial for a stable reference.

Reference Electrode

The concept of a reference electrode, like the Standard Hydrogen Electrode (SHE), is fundamental in electrochemistry. A reference electrode provides a stable and well-characterized point from which the potential of other electrodes can be measured.

The SHE is particularly valuable because it offers a consistent potential of 0 volts under all standard conditions. By measuring against this, scientists can predict how other electrodes will behave in electrochemical cells.

• SHE serves as the industry standard reference electrode.
• Provides consistent and unbiased potential measurement.
• Ensures reliability across various electrochemical experiments.