posted by GWM on .
2.Glycolic acid is often used in “facial peels” and has a Ka of 1.5x10^-4. If a movie star is to have a solution of pH 2.1 applied to her face at night, what concentration of glycolic acid solution should be made up (assuming that it is a monoprotic acid, and that it dissolves freely in water)
HG ==> H^+ + G^-
Ka = (H^+)(G^-)/)HG) = 1.5 x 10^-4
Convert pH 2.1 to (H^+), substitute into Ka expression for (H^+) and (G^-) and solve for (HG). That will give you concn HG in moles/L.
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