Introduction to Stoichiometry

Types of Conversions in Stoichiometry

Moles of Substance A to Moles of Substance B
- Shortest type
- Requires identification of the molar ratio
- Example: Converting moles of SO2 to SO3
Moles of Substance A to Grams of Substance B or Grams of Substance A to Moles of Substance B
- Two-step process
- Example: Converting moles of C3H8 to grams of CO2
Grams of Substance A to Grams of Substance B
- Three-step process
- Example: Converting grams of Al to grams of AlCl3

Given: 3.4 moles of SO2 reacts with excess O2
Balanced Equation: 2 SO2 + O2 → 2 SO3
Steps:
1. Identify molar ratio: 2 moles SO2 : 2 moles SO3
2. Conversion: 3.4 moles SO2 → 3.4 moles SO3

Part A: Given: 2.8 moles of C3H8
- Balanced Equation: C3H8 + 5 O2 → 3 CO2 + 4 H2O
- Steps:
  1. Convert moles of C3H8 to moles of CO2 using molar ratio: 1 mole C3H8 : 3 moles CO2
  2. Molar mass of CO2: 44.01 g/mol
  3. Conversion: Calculate grams of CO2
Part B: Given: 3.8 moles of C3H8
- Similar steps to part A but converting to grams of O2
Part C: Given: 25 g of C3H8
- Steps:
  1. Convert grams of C3H8 to moles
  2. Use the molar ratio to find moles of H2O
  3. Conversion to moles of H2O: Answer in moles
Part D: Given: 38 g of H2O
- Steps:
  1. Convert grams of H2O to moles
  2. Use molar ratio to find moles of CO2
  3. Conversion to moles of CO2: Answer in moles

Part A: Given: 35 g of Al
- Balanced Equation: 2 Al + 3 Cl2 → 2 AlCl3
- Steps:
  1. Convert grams of Al to moles
  2. Use molar ratio to convert to moles of AlCl3
  3. Convert moles of AlCl3 to grams
  4. Answer: grams of AlCl3
Part B: Given: 42.8 g of Al
- Similar steps to part A but converting to grams of Cl2

Types of stoichiometric conversions:
- Moles to moles
- Moles to grams
- Grams to grams
- Grams to moles
Grasping these conversions is key to solving typical chemistry problems efficiently.