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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: jubba on September 07, 2005, 06:06:18 AM

Title: Does heating water to say 50 degrees celcius make it more acidic or more basic?
Post by: jubba on September 07, 2005, 06:06:18 AM
Does heating water to say 50 degrees celciuc make it more acidic or more basic?

I think its neutral as equal amount of hydronium and hydroxide ions will be created.
Can anyone verify or reject this?  :robots:
Title: Re:Acid Bases round 2 (i had an hideous exam)
Post by: jubba on September 12, 2005, 02:37:35 AM
anybody :1eye:
Title: Re:Acid Bases round 2 (i had an hideous exam)
Post by: Borek on September 12, 2005, 03:22:04 AM
Quote from: jubba on September 07, 2005, 06:06:18 AM
Does heating water to say 50 degrees celciuc make it more acidic or more basic?

Depends on how do you define neutral. If H+ = OH- then you are right. If pH=7.00 then you are wrong - Kw value is slightly higher in higher temperatures.
Title: Re:Acid Bases round 2 (i had an hideous exam)
Post by: jubba on September 14, 2005, 11:54:30 PM
the definition was H+=OH-
Title: Re:Acid Bases round 2 (i had an hideous exam)
Post by: Borek on September 15, 2005, 03:29:37 AM
Quote from: jubba on September 14, 2005, 11:54:30 PM
the definition was H+=OH-

So all you have to take into account is the stoichiometry of the water dissociation reaction. Can it produce different amounts of H+ and OH-?
Title: Re:Acid Bases round 2 (i had an hideous exam)
Post by: Mitch on September 16, 2005, 09:09:42 PM
Kw is a function of temperature, that is my hint.
Title: Re: Does heating water to say 50 degrees celcius make it more acidic or more bas
Post by: Donaldson Tan on September 19, 2005, 04:47:01 PM
Kw is no longer 10-14 at 50C. It will be a much bigger value because there is greater extent of dissociation. However, the aqueous system still remains neutral because [H+] = [OH-]
Title: Re: Does heating water to say 50 degrees celcius make it more acidic or more bas
Post by: charco on September 19, 2005, 05:14:14 PM
Acidity is defined by the concentration of [H+] therefore it becomes more acidic. pH is the accepted measure of acidity and not a balance between H+ and OH- ions. At higher temperatures the water dissociation equilibrium moves in the direction of endothermic change further to the RHS i.e. side of the ions. Kw becomes larger and the solution has a lower pH.