Calculating Moles of Glucose from Mass

Key Concepts

• Mole Concept: A mole is a quantity that represents Avogadro's number (approximately (6.022 \times 10^{23})) of something, similar to how a dozen represents 12 of something.
• Molar Mass: The mass of one mole of a substance, usually expressed in grams per mole (g/mol).

Problem Statement

• Calculate the number of moles in a 1.52 kg sample of glucose (C6H12O6).

Steps for Calculation

1. Determine the Molar Mass of Glucose

• Carbon (C):
  • Molar mass = 12.01 g/mol.
  • Contribution = 6 atoms of C = 6 × 12.01 g/mol.
• Hydrogen (H):
  • Molar mass = 1.008 g/mol.
  • Contribution = 12 atoms of H = 12 × 1.008 g/mol.
• Oxygen (O):
  • Molar mass = 16.00 g/mol.
  • Contribution = 6 atoms of O = 6 × 16.00 g/mol.
• Total Molar Mass of Glucose = 6 × 12.01 + 12 × 1.008 + 6 × 16 = 180.16 g/mol.

2. Convert Kilograms to Grams

• Given: 1.52 kg of glucose.
• Conversion: 1.52 kg × 1000 g/kg = 1520 g.

3. Calculate Number of Moles

• Use the formula: [ \text{Number of moles} = \frac{\text{Mass (g)}}{\text{Molar Mass (g/mol)}} ]
• Calculation: [ \frac{1520 \text{ g}}{180.16 \text{ g/mol}} = 8.44 \text{ moles} ]

4. Significant Figures

• Consider significant figures in calculations:
  • 1.52 kg has three significant figures.
  • Final result is rounded to three significant figures: 8.44 moles.

Conclusion

• The 1.52 kg sample of glucose contains approximately 8.44 moles of glucose (C6H12O6).