Question

Nitrogen reacts with a metal to form a compound in which there are three atoms of the metal for each atom of nitrogen. If 1.486

Answer 1

Answer:

$\boxed{\text{6.937 u; X = Li}}$

Explanation:

1. Write the unbalanced equation

X + N₂ ⟶ X₃N

2. Balance the equation and gather all the data.

MM:               28.01

            6X   +   N₂ ⟶ 2X₃N

m/g    1.486   1.000

3. Calculate the moles of N₂

$\text{Moles of N}_{2} = \text{1.000 g N}_{2} \times \dfrac{\text{1 mol N}_{2}}{\text{28.01 g N}_{2}} = \text{0.035 70 mol N}_{2}$

4. Calculate the moles of X

The molar ratio is 6 mol X: 1 mol N₂

$\text{Moles of X} = \text{0.035 70 mol N}_{2} \times \dfrac{\text{6 mol X}}{\text{1 mol N}_{2}} = \text{0.2142 mol X}$

5. Calculate the molar mass of X

$\text{Molar mass} = \dfrac{\text{mass}}{\text{moles}} = \dfrac{\text{1.486 g}}{\text{0.2142 mol}} = \text{6.937 g/mol}\\\text{The molar mass of X is 6.937 g/mol, so the atomic mass \boxed{\textbf{6.937 u}} }$

6. Identify X.

$\text{X has an atomic mass of 6.937 u, so \boxed{\textbf{X = Li}} (at. mass 6.94 u)}$