Chlorhexidine is an antibacterial drug found in mouthwash and has an elemental analysis of 52.28% carbon, 5.98% hydrogen, 14.03% chlorine, and 27.71% nitrogen. It has a molar mass of 505.45 g/mol. What is the molecular formula of chlorhexidine?

Question

Quizplus · Accepted Answer

1) Calculate the empirical formula:
- Assume 100 g of chlorhexidine, which gives the following masses of each element:
  - Carbon: 52.28 g
  - Hydrogen: 5.98 g
  - Chlorine: 14.03 g
  - Nitrogen: 27.71 g
- Convert each mass to moles:
  - Carbon: 52.28 g / 12.01 g/mol = 4.35 mol
  - Hydrogen: 5.98 g / 1.01 g/mol = 5.92 mol
  - Chlorine: 14.03 g / 35.45 g/mol = 0.396 mol
  - Nitrogen: 27.71 g / 14.01 g/mol = 1.98 mol
- Divide each mole value by the smallest mole value (0.396 mol) to get the empirical formula:
  - C11H30ClN2
2) Calculate the molecular formula:
- Divide the given molar mass by the empirical formula mass to get the scaling factor:
  - Scaling factor = 505.45 g/mol / (12.01 g/mol x 11 + 1.01 g/mol x 30 + 35.45 g/mol + 14.01 g/mol x 2) = 5
- Multiply the subscripts in the empirical formula by the scaling factor to get the molecular formula:
  - C55H150Cl5N10

Chlorhexidine Is an Antibacterial Drug Found in Mouthwash and Has