What is the concentration of #OH^-# ions in pure water at 20 degrees Celsius?

Question

#[OH^-]# ion concentration .

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Answer 1 · 2018-04-23T18:11:36

#sf(8.25xx10^(-8)color(white)(x)"mol/l")#

Pure water dissociates:

#sf(H_2OrightleftharpoonsH^(+)+OH^(-))#

#sf(K_w=[H^(+)][OH^(-)]=0.681xx10^(-14))# at #sf(20^@C)#

Since #sf([H^+]=[OH^(-)])# we can say:

#sf([OH^(-)]=sqrt(0.681xx10^(-14))=8.25xx10^(-8)color(white)(x)"mol/l")#