HF is a weak electrolyte because it dissociates into ions in solution. If a solution of HF is placed in contact with a solid metallic electrode, hydrogen gas will form at the surface of the electrode. This behavior is exhibited by most acids and bases in water solutions (acidic solutions in this case).
HF(aq) + e- –> H^+ (aq) + F^- (aq)
If you look at the equation above and compare it to the equation for an electrochemical cell, you will notice that there is no current flow through the solution. The positive hydrogen ions are attracted to the negative terminal of the battery, but they don’t move through the solution because they are ionized into hydrogen gas at the surface of the electrode.
Last modified: August 11, 2022