Key Concepts in Stoichiometry and Combustion Reactions

Combustion of Methane

• Stoichiometric Ratios:
  • One molecule of methane produces two molecules of water.
  • This ratio is consistent for any quantity due to stoichiometric coefficients.
• Calculating Moles:
  • One mole of methane produces two moles of water.
  • Moles are simply a count of items, equivalent to Avogadro's number.
• Example Calculation:
  • If one mole of methane combusts completely:
    • 2 moles of water are produced.
    • Water molecules = 2 moles × Avogadro's number = 1.24 × 10^24 molecules.

Combustion of Hexane

• Reaction Process:
  • Calculate moles of water produced using the stoichiometric ratio.
• Example Calculation:
  • If three moles of hexane combust:
    • Stoichiometric ratio: 3 moles hexane × 10 moles water / 2 moles hexane = 15 moles of water.
    • Water molecules produced = 15 moles × Avogadro's number.

General Principles in Stoichiometric Calculations

• Stoichiometric Ratio Usage:
  • Always convert from moles of reactants to moles of products using the stoichiometric ratio.
• Avogadro’s Number:
  • Use Avogadro’s number to convert from moles to the number of molecules.

Summary

• Stoichiometry allows for the calculation of moles of products from moles of reactants.
• The number of product molecules can be determined by multiplying the moles by Avogadro's number.