Converting Between Grams and Moles in Chemistry

Introduction

• Frequently, in chemistry, we convert between grams and moles for compounds rather than elements.
• Every compound has its own molar mass which is crucial for conversions.

Molar Mass Calculation

• Molar Mass: Expressed in grams per mole, it represents the mass of one mole of a given compound.
• Method: Calculate the molecular mass by summing the atomic masses of all atoms in the compound, then express the total mass in grams per mole.

Example: Glycine

1. Molecular Formula: C₂H₅O₂N
2. Calculating Molecular Mass:
   • Carbon: 2 atoms x 12 = 24
   • Hydrogen: 5 atoms x 1 = 5
   • Oxygen: 2 atoms x 16 = 32
   • Nitrogen: 1 atom x 14 = 14
   • Total Molecular Mass: 75 atomic mass units (amu)
   • Molar Mass: 75 grams per mole
3. Conversion:
   • Given: 28.35 grams of glycine
   • Use dimensional analysis to convert to moles:
   • Result: 0.38 moles of glycine

Example: Vitamin C

1. Molecular Formula: C₆H₈O₆
2. Calculating Molar Mass:
   • Molar mass calculated as 176 grams per mole
3. Conversion:
   • Given: Daily allowance for children = 1.42 x 10⁻⁴ moles
   • Convert to grams:
   • Result: 0.025 grams of Vitamin C

Conclusion

• Converting between grams and moles requires calculating the molar mass and using dimensional analysis.
• This method can be applied to any compound or element to understand the practical quantities in a chemical context.