Does mass equal to moles times molar mass take into account coefficients? I have an equation $$\ce{ 2NaN3 -&gt; 2Na + 3N2}$$ I've calculated there are $\pu{4.4 moles}$ of $\ce{N2}$ (using the data given in the question). I then did $\large{\frac{4.4}{3 \cdot 2}}$ to get number of moles required of $\ce{NaN3}$ (although if this is wrong then correct me). And now I want to calculate the mass of $\ce{NaN3}$ used (knowing there are $\pu{3 moles}$).

Where I have $\pu{ 3 moles}$ of $\ce{2NaN3}$ and I want to calculate mass do I use the $\mathrm{M_r }$of $\ce{M_r(NaN3)\cdot 2}$ or just a single mole of it.

Eg:
 $\text{mass = moles} \cdot  \mathrm{M_r} = 3 \cdot 65 $ or $\text{mass = }~3 \cdot 130$?
What do you mean by $\pu{3 moles}$ of $\ce{ 2NaN3}$? The coefficient (the 2) is the number of moles of that molecule that you have. 

If you're looking at an equation with $\ce{ 2NaN3}$ written in it, and you want that 3 times, then you're going to have $\pu{6 moles}$ of $\ce{NaN3}$, so $\text{mass}~= ~6 \cdot 65$ .