Does the Formation of Water Molecules Affect Temperature?

[Dylanden]

Hello

When mixing a strong acid and water, the temperature increases. There is production of water molecules from H + and OH- ions. If you plunge a glass of pure water into an intense electric field, the ions present in the pure water will migrate. The pH equilibrium will no longer be respected. And water molecules will turn into ions. Will the temperature go down?
Dylan

 

[BvU]

I think the energy comes from the electric field, but I'm very curious to hear from @Chestermiller and @Orodruin about this !

 

[Borek]

The pH equilibrium will no longer be respected.

On the walls of the glass perhaps, I don't expect anything strange to happen in the bulk of the solution. IMHO ions will concentrate in a layer at the border till the electric field they generate neutralizes the external electric field.

 

[Dylanden]

Hello Borek and ByU.
I have found an old experience of Aarhénius (the man who discover the existence of ions in water).
Indeed, if we put a glass of water (or a solution of KCl) in an elctric field, the ions will migrate to the wall.
1/ I think that in pure water, we must always have a pH of 7. A concentration of H+ (and OH-) about 10 exp-7.
If some ions go on the wall of the glass, the concentration in the bulk of the water will decrease.
And H2O <> H+ and OH-. And this this an endothermic réaction when molécule "open".
2/ With solution of a salt, we have other phenomens. And perhaps also trhermic effect.
Can we use that as a heating pump?

Dylan

 

[Bystander]

If some ions go on the wall of the glass, the concentration in the bulk of the water will decrease

Says who?

 

[Borek]

Define what you mean by

an intense electric field

then estimate amount of ions required to create such a filed of an opposite sign.

 

[Dylanden]

Hello

Well well. I don't know... About lot of thing.
I have seen an experience of Aarhenius in an old book.
Where it is showed that ions K+ and Cl- migrate in a solution if we put two charged electrodes not in the solution.
But outside the glass. It is the electrostatic.
Is that propertie can be used for something. I am looking for.

I know that when we mix together acid and base, in solution, the water can became very hot. Steam.
I also know that to decompose one mole water, we need 96500 Coulomb. Onder 2Volt.

But here, it seems that the charges do not circule. There are there.

Dylan

 

[Dylanden]

And.

The charge and the discharge of a capacitor is a reversible transformation.

Dylan

 

[Dylanden]

Hello.

What i try to explain.
We have a closed container. In glass. Filled with water. At room temperature.
We approch two charged electrodes. Ions (not all ions) migrate. The temperature decrease
Ambiance give calorie to the container. It goes back to room temperature.
One discards charged electrodes.
The temperature of the water increase. Over room temperature.
We can heat something.

I add.
The mechanical energy to approach and remove the electrodes gives a theoretical null balance.

Dylan