$20\, mL \,0.1\, M\, NH _4 OH$ ને $40\, mL \,0.05 \,M\, HCl$ સાથે મિશ્ર કરવામાં આવ્યો. તો આ મિશ્રણની $.....\,pH$ છે.

(આપેલ : $K _{ b }\left( NH _4 OH \right)=1 \times 10^{-5}, \log 2=0.30, \log 3=0.48, \log 5=0.69, \log 7=0.84, \log 11=$ $1.04)$

Question

$20\, mL \,0.1\, M\, NH _4 OH$ ને $40\, mL \,0.05 \,M\, HCl$ સાથે મિશ્ર કરવામાં આવ્યો. તો આ મિશ્રણની $.....\,pH$ છે.

(આપેલ : $K _{ b }\left( NH _4 OH \right)=1 \times 10^{-5}, \log 2=0.30, \log 3=0.48, \log 5=0.69, \log 7=0.84, \log 11=$ $1.04)$

JEE MAIN 2022, Medium

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Solution

c
$NH _{4} OH + HCl \rightarrow NH _{4} Cl + H _{2} O$

$\left[ NH _{4}^{+}\right]=\frac{2\,m\,mole }{60\,ml }=\frac{1}{30}\,M$

$pH =\frac{ pK _{ w }- pK _{ b }-\log C }{2}=\frac{14-5+1.48}{2}=5.24$

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