Lecture on Mole Ratio and Stoichiometry

Introduction to Mole Ratio

Mole ratio is a concept used in chemistry to express the ratio between the amounts in moles of any two compounds involved in a chemical reaction.
It is derived from the coefficients of a balanced chemical equation.

Reaction: Nitrogen gas (N2) reacts with hydrogen gas (H2) to produce ammonia (NH3).
Balanced Equation: N2 + 3H2 → 2NH3
- Coefficients give the mole ratio: 1:3:2 (N2:H2:NH3)
- 1 mole of N2 reacts with 3 moles of H2 to produce 2 moles of NH3.
Extended Ratios:
- 2 moles N2 react with 6 moles H2 to produce 4 moles NH3.
- 3 moles N2 react with 9 moles H2 to produce 6 moles NH3.
Problem: Calculate moles of H2 needed for 1.5 moles of N2.
- Conversion: 1.5 moles N2 * (3 moles H2 / 1 mole N2) = 4.5 moles H2.*

Reaction: Propane (C3H8) reacts with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O).
Balanced Equation: C3H8 + 5O2 → 3CO2 + 4H2O
Problem: Find moles of O2 required to produce 14 moles of H2O.
- Ratio: 5 moles O2 produce 4 moles H2O.
- Estimation: Between 15 and 20 moles O2 for 14 moles H2O.
- Calculation: 14 moles H2O * (5 moles O2 / 4 moles H2O) = 17.5 moles O2.*

Reaction: Ammonia (NH3) reacts with oxygen (O2) to produce nitrogen gas (N2) and water (H2O).
Balanced Equation: 4NH3 + 3O2 → 2N2 + 6H2O
Part A: Find moles of O2 needed for 11 moles of NH3.
- Ratio: 4 moles NH3 react with 3 moles O2.
- Calculation: 11 moles NH3 * (3 moles O2 / 4 moles NH3) = 8.25 moles O2.
Part B: Find moles of H2O produced from 11 moles of NH3.
- Ratio: 4 moles NH3 produce 6 moles H2O.
- Calculation: 11 moles NH3 * (6 moles H2O / 4 moles NH3) = 16.5 moles H2O.

Understanding mole ratio is crucial for solving stoichiometry problems in chemistry.
Practice with various examples helps in mastering the concept.
Ensure chemical equations are balanced before performing mole ratio calculations.