Question

If you need to make 240 g lioh, how many grams of li3n must you react with excess water?

Answer 1

Answer is: 116,1 g of Li₃N.
Chemical reaction: Li₃N + 3H₂O → 3LiOH + NH₃.
m(LiOH) = 240g.
n(LiOH) = m(LiOH) ÷ M(LiOH).
n(LiOH) = 240 g ÷ 24 g/mol = 10 mol.
from chemical reaction: n(LiOH) : n(Li₃N) = 3 : 1.
10 mol : n(Li₃N) = 3 : 1.
n(Li₃N) = 3,33 mol.
m(Li₃N) = n(Li₃N) · M(Li₃N)
m(Li₃N) = 3,33 mol · 34,85 g/mol = 116,1 g.

Answer 2

117 g would be the best bet for this question.