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What is the pH of millimolar solution of ammonium hydroxide which is 20% dissociated ?A. 3.699B. 10.301C. 4.691D. 9.301 |
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Answer» Correct Answer - B Concentration of `NH_(4)OH` solution = 0.001 M Degree of dissociation = `20 % = (20)/(100) = 0.2` Concentration of `OH^(-)` i.e., `[OH^(-)] =` Concentration of solution `xx` degree of dissociation `= 0.001 xx 0.02 = 2 xx 10^(-4)` `because [H^(+)] [OH^(-)] = 1 xx 10^(-14)` `therefore [H^(+)] = (1 xx 10^(-14))/(2 xx 10^(-4)) = (1)/(2) xx 10^(-10)` Again `, because p H = - log [H^(+)]` `therefore pH = - log ((1)/(2) xx 10^(-10))` = `- log (-10 - 0.3010) = 10.3010` |
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