Lecture Notes: Calculating Molar Mass and Converting Grams to Moles

Introduction

• Presenter: Melissa Maribel
• Focus: Understanding molar mass, converting grams to moles and vice versa
• Audience: Students serious about Chemistry

Types of Mass in Chemistry

• Atomic Mass
  • Measured in atomic mass units (amu)
• Molar Mass
  • Measured in grams per mole (g/mol)
  • Represents the mass of a mole of an element

Calculating Molar Mass

• Individual Element Example: Carbon
  • Use periodic table: Carbon = 12.011
  • Molar mass: 12.011 g/mol
• Compound Example: Carbon Dioxide (CO2)
  • Carbon: 12.011 g/mol + Oxygen: 2 × 16 g/mol = 32 g/mol
  • Total molar mass: 44.011 g/mol

Conversion Factors

• Conversion factors involve two different units (e.g., grams and moles)
• Molar Mass serves as a conversion factor
  • Useful for converting between grams and moles

Example 1: Converting Grams to Moles

• Problem: How many moles in 5.3 grams of iron chloride?
• Given: 5.3 grams iron chloride
• Find: Moles of iron chloride
• Plan: Convert using molar mass
  • Molar Mass of Iron Chloride: Iron = 55.85, Chlorine = 35.45 × 2
  • Total: 126.75 g/mol
• Calculation:
  • Setup conversion with units aligned to cancel
  • Result: 0.042 moles of iron chloride

Example 2: Converting Moles to Grams

• Problem: Find the mass of 0.30 moles of magnesium nitrate
• Given: 0.30 moles magnesium nitrate
• Find: Grams of magnesium nitrate
• Plan: Convert using molar mass
  • Molar Mass of Magnesium Nitrate: Magnesium = 24.31, Nitrogen = 14.01 × 2, Oxygen = 16 × 6
  • Total: 148.33 g/mol
• Calculation:
  • Setup conversion to align units for cancellation
  • Result: 44 grams of magnesium nitrate (considering two significant figures)

Conclusion

• Encouragement to practice conversions
• Offer for free live tutoring and additional resources
• Call to action to subscribe and engage with further content

• Note: Practice problems and tutoring resources are available for further study.