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# Variation of ph value of water with temperature

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## Variation of ph value of water with temperature

(OP)
Dear sir,
I would like to know the variation in ph value of water with temperature.
Thanks & Best Regads
Mehaboob.P.K

### RE: Variation of ph value of water with temperature

Don't have a graph handy, but the neutral point is ~5.5 at 300 deg C, IIRC.

### RE: Variation of ph value of water with temperature

The dissociation constant for water increases with T (Log KW becomes less negative) according to

Log KW = -4470.99/T + 6.0875 - 0.01706 T

where T is degrees K, and pH = -0.5 x Log KW.
For 573 K, this equation gives pH = -5.7 cf. the ~5.5 value given by Metalguy.
Source: M. Whitfield, in Chemical Oceanography, J. P. Riley and Skirrow, Eds., Vol. 1, 2nd ed., Academic, New York, 1975, pp. 44-171. Cited by
http://antoine.frostburg.edu/chem/senese/101/acidbase/faq/temperature-dependence-Kw.shtml#Whitfield

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