Question

11.5 grams of sodium metal are placed in a container with excess chlorine gas. Once the reaction is complete, 29.0 grams of sodium chloride are measured. What mass, in grams, of chlorine gas reacted?

Answer 1

Answer:

• 17.6 g of chlorine gas reacted.

Explanation:

1) Chemical equation:

• 2Na + Cl₂ (g) → 2NaCl (s)

2) Mole ratios:

• 2 mol Na : 1 mol Cl₂ : 2 mol NaCl

3) Number of moles of sodium chloride (NaCl) measured (produced):

• Number of moles = mass in grams / molar mass

• Molar mass of NaCl = 58.44 g/mol

• Number of moles of NaCl = 29.0 g / 58.44 g/mol = 0.496 mol

4) Number of moles of chlorine gas (Cl₂) reacted:

• From the stoichiometric mole ratios:

       1 mol Cl₂ / 2 mol NaCl = x / 0.496 mol NaCl

       x = 0.496 mol NaCl / 1 mol Cl₂ / 2 mol NaCl = 0.248 mol Cl₂.

5) Convert 0.248 mol Cl₂ into mass in grams:

• mass in grams = molar mass × number of moles

• molar mass of Cl₂ = 70.9 g/mol

• mass in grams = 70.9 g/mol × 0.248 mol = 17.6 g ← answer