(a) Write the half-reaction that occurs at a hydrogen electrode in acidic aqueous solution when it serves as the anode of a voltaic cell. (b) The platinum electrode in a standard hydrogen electrode is specially prepared to have a large surface area. Why is this important? (c) Sketch a standard hydrogen electrode.

When the hydrogen electrode serves as the anode of a voltaic cell, it undergoes oxidation. Oxidation is a process in which an element loses electrons. Since the hydrogen electrode is in an acidic aqueous solution, hydrogen ions (H⁺) are available in the solution. In the oxidation process, hydrogen gas (H₂) is converted into hydrogen ions (H⁺) by losing two electrons. The oxidation half-reaction for this process is as follows: \(H_2(g) \rightarrow 2H^+(aq) + 2e^-\) #b) Importance of a large surface area for the platinum electrode#

The platinum electrode in a standard hydrogen electrode is specially prepared with a large surface area, which is critical for its function. A large surface area for the platinum electrode allows more hydrogen gas molecules to come into contact with the electrode surface. As a result, more redox reactions can occur at the electrode surface, leading to better electron transfer and greater overall efficiency of the electrochemical cell. #c) Sketch a standard hydrogen electrode#

To sketch a standard hydrogen electrode, follow these guidelines: 1. Draw a glass tube with a small opening at one end. 2. Insert the platinum electrode inside the glass tube, with the top covered with a protective cap. The electrode should have a porous surface to represent the large surface area. 3. Attach a wire to the platinum electrode to connect it to the external circuit. 4. Below the electrode, draw a bulb-shaped container, which is the reservoir for the acidic aqueous solution (1M H₃O⁺ ions) and some hydrogen gas (H₂). 5. Draw a thin, flat sheet of platinum attached to the platinum electrode, partially submerged in the solution. This sheet allows the passage of hydrogen gas to come into contact with the electrode. 6. Add labels for each component: platinum electrode, hydrochloric acid solution, hydrogen gas, and the external wire connection. Use this sketch as a visual aid when discussing the components and function of a standard hydrogen electrode.