# Does the temperature of water change during electrolysis?

Applying an electric potential to impure water splits water into its constituents H/O.

Does the temperature of the electrolyte change during this electrolysis?

• ""Applying an electric potential to impure water splits water into it's constituent H/O."" This is wrong, just "potential" does change nothing. One needs to have a current flowing to achieve electrolysis. And if you read a physics book first, you may learn about currents and heat. – Georg Aug 25 '13 at 18:53
• Because the electrolyte has a finite resistance, heat will be generated based on the power, $I^2R$, the time of electrolysis (since $power=\frac{energy}{time}$) and the heat capacity $C=\frac{energy_{heat}}{\Delta T}$. This would be a very rough estimate since it assumes the solution is the greatest source of resistance. – bobthechemist Aug 26 '13 at 1:33
• However, Wikipedia states that there are cases where the temperature drops because of the electrolysis (“in the electrolysis of steam into hydrogen and oxygen at high temperature, […] heat is absorbed from the surroundings”). So it may not be as easy as Joule effect… – F'x Aug 26 '13 at 8:05
• @F'x Interesting point, although this is a case where a reference on the Wikipedia page would be beneficial since this is a fairly unexpected phenomenon. – bobthechemist Aug 26 '13 at 11:20