Saturday, January 5, 2019

electrochemistry - Hydrogen fuel cell - why do the H+ ions move through the electrolyte



Consider the following hydrogen fuel cell fuel cell


http://butane.chem.uiuc.edu/pshapley/Enlist/Labs/FuelCellLab/FuelCell.html


At the anode, hydrogen is oxidised (losing electrons). My first question is this: why is the anode negative if it is attracting electrons?


My second question refers to the fact that once the hydrogen atoms are iodised, the H+ ions move through the electrolyte towards the oxygen ions at the cathode, reacting to form water. If the anode is negative, why would positive H+ ions move away from it?



Answer




At the anode, hydrogen is oxidised (losing electrons). My first question is this: why is the anode negative if it is attracting electrons?



It is not attracting electrons, it is attracting hydrogen atoms. The electrode binds the hydrogen and releases the electrons. The electrons are then able to flow out through the wire.




My second question refers to the fact that once the hydrogen atoms are iodised, the H+ ions move through the electrolyte towards the oxygen ions at the cathode, reacting to form water. If the anode is negative, why would positive H+ ions move away from it?



Once the electrons have returned to the cathode, the cathode is more negative than the anode. The positive ions move to the cathode and the negative ions move to the anode.


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