text: calculate the [oh-] of an aqueous solution with the following [h30+]? please help, this wasnt taught in class and its in the hw.    coffee, 1.0 x 10 -5m  soap, 1.0 x 10 -8 m ph + poh = 14 coffe : ph = 5 => poh = 9 => [oh-] = 10^-9 m soap : ph = 8 => poh = 6 => [oh-] = 10^-6m