Question

Which is not true for a standard hydrogen electrode?

Options

• The pressure of hydrogen is 1 atm.

• The hydrogen ion concentration is 1 M.

• Temperature is 25°C.

• H₂ gas is not absorbed by platinum electrode.

Answer 1

H₂ gas is not absorbed by platinum electrode.

Explanation:

In a standard hydrogen electrode (SHE):

• Hydrogen gas is maintained at 1 atm pressure.
• Hydrogen ion concentration is 1 M.
• Temperature is 25°C (298 K).
• Platinum electrode absorbs H₂ gas to facilitate the reversible redox reaction.
  \[\ce{2H+ + 2e- <=> H2_{(g)}}\]

Therefore, it is incorrect to say that H₂ gas is not absorbed. Actually, platinum is essential for effectively transferring electrons by adsorbing hydrogen gas.