Question

Determine the number of moles of N atoms in 46.5g of Mg(NO3)2

Answer 1

First, we determine the moles of Mg(NO₃)₂ present:
moles = mass / Mr
= 46.5 / (24 + 2 x (14 + 16 x 3))
= 0.4 mole

Each mole of Mg(NO₃)₂ contains 2 moles of Nitrogen atoms.
Moles Nitrogen = 0.4 x 2
= 0.8 mole