Answer:
The percentage by mass of lithium in one mole of Li₃N is approximately 59.78%
Step-by-step explanation:
The given compound is Li₃N
The atomic mass of lithium, Li = 6.94 amu
The atomic mass of nitrogen, N = 14.01 amu
Therefore by definition, we have;
The mass of one mole of lithium, Li = 6.94 g
The mass of one mole of nitrogen, N = 14.01 g
One molecule of Li₃N contains 3 atoms of lithium, Li and 1 atom of nitrogen, N
The mass of one mole of Li₃N = The molar mass of Li₃N = 3 × The mass of one mole of lithium + The mass of one mole of nitrogen
∴ The mass of one mole of Li₃N = 3 × 6.94 g + 14.01 g = 34.83 g
The percentage by mass of lithium, Li, in one mole of Li₃N = 3×6.94/(34.83) × 100 ≈ 59.78%
The percentage by mass of lithium in one mole of Li₃N ≈ 59.78%.