Question

A 0.010 M solution of PuO2(NO3)2 was found to have pH of 4.0.what is hydrolysis constant Kh for PuO2^2+ and what is Kh for PuO2OH^+?

Answer 1

Answer:

Consider the reaction

$PuO_{2} (NO_{3})_{2}  +H_{2} O--->PuO^{2+} _{2} +NO^{2-} _{3} +H_{3} O^{+}$

Now given pH=4.0

using henderson hasselbach equation

$pH=pKa+log[PuO_{2} ^{2+} ][H_{3} O^{+} ]/[PuO_{2} (NO_{3} )_{2} ]$

4.0=pKa+log(0.010)

4.0=pKa+(-2)

pKa=6

Ka=-antilog(6)

    =$1.60*10^{-6}$

$K_{W} =10^{-14}$

Now hydrolysis constant for $PuO^{2+} _{2}$

$K_{h} =K_{W} /K_{a}$

$=6.3*10^{-7}$