Question

What mass of lithium reacts to produce 87.2 grams of Li3N?



6 Li(s) + N2(g) → 2 Li3N(s)

Answer 1

Molar mass of $Li_3N$ is 35 gms.

Thus $87.2 grams =87.2/35 moles$ .

1 mole $Li_3N$ reacts with 3 moles of Li

Thus Lithium required is $87.2*3/35 moles$

Atomic mass of Li is 7 gms.

Thus, mass of lithium required is

$87.2*3*7/35=52.32 gms.$