## neutral pH not 7?

$\ln K = -\frac{\Delta H^{\circ}}{RT} + \frac{\Delta S^{\circ}}{R}$

He whose name cannot be spoken
Posts: 20
Joined: Sat Apr 28, 2018 3:00 am

### neutral pH not 7?

I thought the neutral pH is when [H+] and [OH-] were the same, which is at pH=pOH=7.

Is that not always the case?

Ashish Verma 2I
Posts: 59
Joined: Fri Sep 28, 2018 12:28 am

### Re: neutral pH not 7?

pH 7 is neutral at STP but not for all temperatures as Kw is temperature dependent.

eden tefera 2B
Posts: 39
Joined: Fri Sep 28, 2018 12:21 am

### Re: neutral pH not 7?

Using the vant hoff equation can help you see how temperature affects K. From there you can determine if a certain pH is neutral.

hazelyang2E
Posts: 57
Joined: Fri Sep 28, 2018 12:23 am

### Re: neutral pH not 7?

pH is not neutral at 7 if the conditions are not standard. A pH of 7 may be acidic or basic depending upon the pH at nonstandard conditions.

Lisa Werner 2F
Posts: 72
Joined: Fri Sep 28, 2018 12:17 am

### Re: neutral pH not 7?

at different temperatures, ph 7 is not always neutral.

Roberto Gonzalez 1L
Posts: 39
Joined: Fri Sep 28, 2018 12:17 am

### Re: neutral pH not 7?

Kw is temperature dependent and therefore the concentration of [h30+] and [oh-], calculated by the square root of Kw, will be different.

Anita Wong 1H
Posts: 68
Joined: Fri Sep 28, 2018 12:27 am
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### Re: neutral pH not 7?

its different at varying temperatures