What is the mass percent of lithium in lithium nitride (Li3N)?

• A. 25.7%
• B. 59.0%
• C. 87.5%
• D. 43.4%

Answer: (B)

Verified step by step guidance

1. Identify the chemical formula of lithium nitride, which is \(\mathrm{Li_3N}\), meaning it contains 3 lithium (Li) atoms and 1 nitrogen (N) atom per formula unit.
2. Find the atomic masses of lithium and nitrogen from the periodic table: lithium (Li) has an atomic mass of approximately 6.94 g/mol, and nitrogen (N) has an atomic mass of approximately 14.01 g/mol.
3. Calculate the total molar mass of lithium nitride by summing the masses of all atoms in the formula: \$3 \times 6.94\( g/mol for lithium plus \)1 \times 14.01$ g/mol for nitrogen.
4. Calculate the total mass of lithium in the compound by multiplying the number of lithium atoms by the atomic mass of lithium: \$3 \times 6.94$ g/mol.
5. Determine the mass percent of lithium in lithium nitride using the formula: \(\text{Mass \% Li} = \left( \frac{\text{Mass of Li}}{\text{Molar mass of } \mathrm{Li_3N}} \right) \times 100\%\).