Which of the following statements about the standard hydrogen electrode is not correct?

Analyze the question: We need the statement about the standard hydrogen electrode (SHE) that is not correct.

Concept: The SHE is the reference electrode used to measure standard electrode potentials. By definition its potential is exactly 0.00 V. The standard conditions are:

• Hydrogen gas at a pressure of 1 atm (101.3 kPa)
• H⁺(aq) solution at a concentration of 1 mol dm⁻³
• An inert platinum electrode, coated with platinum black, which adsorbs the hydrogen gas and conducts electrons
• A temperature of 25 °C (298 K)

Check each option:

• A. Hydrogen at 1 atm is correct.
• B. 1 mol dm⁻³ H⁺(aq) is correct.
• C. A platinum electrode is correct. It is inert and provides a surface for the reaction 2H⁺ + 2e⁻ ⇌ H₂.
• D. A temperature of 20 °C is not correct. The standard temperature is 25 °C (298 K).

Tip: Remember the SHE as "1, 1, Pt, 25": 1 atm, 1 mol dm⁻³, platinum, 25 °C. If an option gives a different temperature, such as 20 °C, it is probably the false statement.