Answer
$135\text{ grams $NaN_3$}$
Work Step by Step
$70.0 \text{ L $N_2$}*\frac{1\text{ mol $N_2$}}{22.42\text{ L $N_2$}}*\frac{2 \text{ mol $NaN_3$}}{3 \text{ mol $N_2$}}*\frac{65.0099 \text{ grams $NaN_3$}}{1 \text{ mol $NaN_3$}}=135\text{ grams $NaN_3$}$