what is the acid dissociation constant ka of water?

[Smooth Operater]

what is the acid dissociation constant ka of water?

the answer is 1.8e-16, but how would you get it?

I first thought it is 1.0e-7, but apparently I am wrong.

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[doc toothache]

Tlhe dissociation constants (Kw) of water are measured experimentally and are temperature dependent.

at -35 C...1 x 10e-17 (pH 8.5)
at 0 C...1.12 x 10e-15 (pH 7.5)
at 25 C...1 x 10e-14 (pH 7)
at 30 C...1.8 x 10e-14
at 50 C...9.311 x 10e-14 (pH 6.5)

 

[Mr. Tee]

Tlhe dissociation constants (Kw) of water are measured experimentally and are temperature dependent.

at -35 C...1 x 10e17 (pH 8.5)
at 0 C...1.12 x 10e15 (pH 7.5)
at 25 C...1 x 10e14 (pH 7)
at 30 C...1.8 x 10e14
at 50 C...9.311 x 10e14 (pH 6.5)

10^n, not 10en

 

[MaxillofacialMN]

what is the acid dissociation constant ka of water?

the answer is 1.8e-16, but how would you get it?

I first thought it is 1.0e-7, but apparently I am wrong.

[FONT=Helvetica, Arial]

That's why. You were probably thinking that because the the pH of water is 7. Remember: pH is based on hydronium concentration.
.

 

[loveoforganic]

[h3o+][oh-] / [h2o]

=(1*10^-7)(1*10^-7) / 55.6 = 1.8*10^-16

 

[PreparationIsKey]

Tlhe dissociation constants (Kw) of water are measured experimentally and are temperature dependent.

at -35 C...1 x 10e-17 (pH 8.5)
at 0 C...1.12 x 10e-15 (pH 7.5)
at 25 C...1 x 10e-14 (pH 7)
at 30 C...1.8 x 10e-14
at 50 C...9.311 x 10e-14 (pH 6.5)

From what I can deduce H2O --> H+ + OH- is an endothermic reaction as seen for the equilibrium shift to the right due to temperature increase. Am I correct?