To determine the limiting reactant, you need to compare the moles of each reactant and see which one is present in the smallest amount relative to the stoichiometry of the balanced chemical equation.
1. First, calculate the moles of each reactant:
For silicon (Si):
- Mass of Si = 2 grams
- Molar mass of Si = 28.09 g/mol (from the periodic table)
- Moles of Si = Mass / Molar mass = 2 g / 28.09 g/mol ≈ 0.071 mol
For nitrogen gas (N₂):
- Mass of N₂ = 1.50 grams
- Molar mass of N₂ = 28.02 g/mol (from the periodic table)
- Moles of N₂ = Mass / Molar mass = 1.50 g / 28.02 g/mol ≈ 0.053 mol
2. Next, examine the stoichiometry of the balanced chemical equation for the reaction between silicon and nitrogen gas (assuming silicon nitride formation):
Si + 3N₂ → Si₃N₄
From the balanced equation, it shows that 1 mole of silicon reacts with 3 moles of nitrogen gas to form 1 mole of silicon nitride (Si₃N₄).
3. Determine the limiting reactant:
To react completely, 1 mole of silicon requires 3 moles of nitrogen gas. However, there are only approximately 0.053 moles of nitrogen gas available, which is less than what is needed. So, nitrogen gas is the limiting reactant.
Therefore, nitrogen gas (N₂) is the limiting reactant in this reaction.
