$(4)$ Calculate the $pH$ of the solution obtained by titrating $200\mathrm{.}0mL$ of $0\mathrm{.}0250MNN{O}_2($aq$)$ with $65\mathrm{.}0(3)$ Calculate the $pH$ of a $1\mathrm{.}00L$ buffer solution that is $0\mathrm{.}100M$ in $HF(K_a=6\mathrm{.}80{10}^{-4})$ and $0\mathrm{.}150M$ in

NaF.

$[PH=-(3\mathrm{.}17)+0\mathrm{.}176][k_9=6\mathrm{.}8{10}^{-4}]$

$[PH=3\mathrm{.}17+0\mathrm{.}176$

$[1+F]=0\mathrm{.}100m]$

$[pH=3\mathrm{.}35$

$[A^{-}]=[NqF]=0\mathrm{.}150M]$

$[tHA]=[1+F]=0\mathrm{.}100,M$

$(3)$ Calculate the $pH$ of the buffer after the addition of $10\mathrm{.}0mL$ of $0\mathrm{.}200$MNaOH.

$mL$ of $0\mathrm{.}15$MNaOH$(aq).$