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How much of 0.3 M ammonium hydroxide should be mixed with 30 mL of 0.2 M solution of ammonium chloride to give a buffer solution of pH 10. Given `pK_(b)` for `NH_(4)OH` is 4.75. |
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Answer» Correct Answer - 112.5 mL `pOH = 14 - pH = 14 - 0 = 4 ` `pOH = pK_(b) + log .(["Salt"])/(["Base"]), 4= 4.75 + log.(["Salt"])/(["Base"]) or log.(["Salt"])/(["Base"]) = - 0.75 = 1.25 or (["Salt"])/(["Base"]) = 0.1778` i.e.,`("Moles of salt")/("Moles of base")=0.1778 or ((0.2)/(1000)xx30)/((0.3)/(1000)xxV)=0.1778` or `V = 112.5 ml` |
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