3.7

$c\left(N_2O_4\right)=\frac{24{,}4mmol}{0{,}372l}=0{,}06559139...$
$c\left(NO_2\right)=0{,}0016136$

$\begin{array}{l|l} &N_2O_4&2\ NO_2\\ \hline c_{alku}&0{,}065591&0\\ muutos&-\frac{1}{2}\cdot0{,}016136&+0{,}016136\\ c_{tasap}&0{,}057523&0{,}16136 \end{array}$

$K_c=\frac{\left(NO_2\right)^2}{N_2O_4}=0{,}04526371...\approx0{,}453\ \frac{mol}{dm^3}$

$K_c=\frac{\left(\frac{mol}{dm^3}\right)^2}{\frac{mol}{dm^3}}=\frac{mol}{dm^3}$