Determining the Empirical Formula of a Mystery Molecule

Problem Statement

• We have a container with a mystery molecule
• The composition by mass:
  • 73% Mercury (Hg)
  • 27% Chlorine (Cl)

Objective

• Determine the empirical formula based on mass composition
• Use periodic table for atomic masses

Methodology

Step 1: Assume Total Mass

• Assume total mass of the molecule: 100 grams
  • Simplifies calculations

Step 2: Calculate Moles of Each Element

• Mercury (Hg):

  • Mass: 73 grams
  • Atomic mass of Hg: 200.59 g/mol
  • Moles of Hg:
    • [ 73 \div 200.59 = 0.36 \text{ moles} ]

• Chlorine (Cl):

  • Mass: 27 grams
  • Atomic mass of Cl: 35.45 g/mol
  • Moles of Cl:
    • [ 27 \div 35.45 = 0.76 \text{ moles} ]

Step 3: Determine the Mole Ratio

• Mercury to Chlorine mole ratio:

  • Hg : Cl
  • 0.36 moles : 0.76 moles

• Simplify the ratio:

  • Ratio is almost 1:2 (Hg:Cl)
  • For every 1 Hg, there are about 2 Cl atoms

Step 4: Determine Empirical Formula

• Simplified ratio: 1 Hg : 2 Cl
• Likely empirical formula: HgCl₂
• Named Mercury (II) Chloride

Conclusion

• Based on mass composition and calculations, the likely empirical formula for the mystery molecule is HgCl₂