Pure Water

[Studyinghard]

I dont get it, at all!

Does pure water always remain pure? but the temperature can decrease the pH but not increase. ?

[fady_22]

Pure water is always neutral, as [H+]=[OH-], regardless of pH.

[Studyinghard]

but the pH of water can never increase right?

[Shack05]

The self ionization of water is endothermic,
so as you increase the temperature it pushes the reaction forwards
so the concentration of H3O and OH increase the same, but the pH decreases,

[Potter]

It can as the ionization of water is endothermic. If you increase the temp, the reaction goes forward. As pH = -log[H+], although the solution remains neutral the pH changes.

[Studyinghard]

It can as the ionization of water is endothermic. If you increase the temp, the reaction goes forward. As pH = -log[H+], although the solution remains neutral the pH changes.

When the reaction goes forward both concentration of H+ and OH- increase but does the H+ overpower OH-? like dont they increase in the same concentration therefore should remain on the same pH?

[fady_22]

It can as the ionization of water is endothermic. If you increase the temp, the reaction goes forward. As pH = -log[H+], although the solution remains neutral the pH changes.

When the reaction goes forward both concentration of H+ and OH- increase but does the H+ overpower OH-? like dont they increase in the same concentration therefore should remain on the same pH?

pH is dependant on the concentration of H+ only.
If you were to decrease the temperature, for example, the system will partially oppose this by shifting to the left. This decreases both the concentration of both H+ and OH-. Considering only the concentration of H+, the pH would thus increase.

[Studyinghard]

It can as the ionization of water is endothermic. If you increase the temp, the reaction goes forward. As pH = -log[H+], although the solution remains neutral the pH changes.

When the reaction goes forward both concentration of H+ and OH- increase but does the H+ overpower OH-? like dont they increase in the same concentration therefore should remain on the same pH?

pH is dependant on the concentration of H+ only.
If you were to decrease the temperature, for example, the system will partially oppose this by shifting to the left. This decreases both the concentration of both H+ and OH-. Considering only the concentration of H+, the pH would thus increase.

ah touche, i think i get it. okay to summarise.

Pure water always remains neutral but since the reaction is endothermic increasing temperature will lead to a forward reaction therefore decreasing pH and increasing pOH. and vice versa if you decrease the temperature. yes?

[JinXi]

Tomorrow's the day water get's you back for abusing it for the past 18 years. Beware

[fady_22]

It can as the ionization of water is endothermic. If you increase the temp, the reaction goes forward. As pH = -log[H+], although the solution remains neutral the pH changes.

When the reaction goes forward both concentration of H+ and OH- increase but does the H+ overpower OH-? like dont they increase in the same concentration therefore should remain on the same pH?

pH is dependant on the concentration of H+ only.
If you were to decrease the temperature, for example, the system will partially oppose this by shifting to the left. This decreases both the concentration of both H+ and OH-. Considering only the concentration of H+, the pH would thus increase.

ah touche, i think i get it. okay to summarise.

Pure water always remains neutral but since the reaction is endothermic increasing temperature will lead to a forward reaction therefore decreasing pH and increasing pOH. and vice versa if you decrease the temperature. yes?

Exactly.