Stoichiometry Lecture Notes

Introduction to Stoichiometry

• Stoichiometry involves understanding measurement of elements and compounds.
• There are four main types of stoichiometry problems:
  • Moles to moles
  • Moles to mass
  • Mass to moles
  • Mass to mass
• Stoichiometry is compared to baking, where correct measurements of ingredients lead to desired products.

Chemical Naming Example

• Example compound: COCl2.6H2O
  • C (Carbon) + O (Oxygen) = CO = Carbon monoxide
  • C (Cobalt) + Cl = Cobalt chloride
  • Cobalt has two types (II and III); here it's Cobalt (II) because of the subscript.
  • The dot and 6 indicate it's a hexahydrate (6 water molecules).
  • Final name: Cobalt (II) chloride hexahydrate.

Key Concepts in Stoichiometry

• Stoichiometry Breakdown:

  • "Stoichio" = element, "metri" = measurement.
  • Stoichiometry relates to the elemental nature of substances.

• Skills to Master in Stoichiometry:

  1. Balancing chemical equations.
  2. Determining stoichiometric coefficients (only after balancing).
  3. Understanding mole ratios.
  4. Differentiating between ideal and limiting reactant stoichiometry.
  5. Solving various stoichiometry problems.

Patterns of Stoichiometry Problems

1. Mole-to-Mole Conversions: Easiest, requires one step.
2. Mole-to-Mass / Mass-to-Mole: Two steps.
3. Mass-to-Mass: Most complex, requires three steps.

Balancing Chemical Equations

• Must be balanced for accurate stoichiometric calculations.
• Use coefficients to adjust amounts of each component in the reaction.

Example of Balancing

1. Examine the number of atoms for each element on both sides of the equation.
2. Adjust coefficients to balance the equation.

Example Reaction Coefficient Calculation

• Coefficients from a balanced equation represent relative amounts of reactants and products.

Mole Ratios

• Ratios can be derived from coefficients in a balanced equation, allowing calculations between different substances in a reaction.
• Example: 6 moles of AGI react with 1 mole of Fe2CO3.

Ideal vs. Limiting Reactant Stoichiometry

• Ideal Stoichiometry: Assumes perfect conditions without limiting reactants.
• Limiting Reactant Stoichiometry: More realistic, accounts for reactants that limit the amount of product formed.
  • Example: If you run out of one ingredient, it limits how much product you can make (e.g., cake analogy).

Practical Examples and Practice Problems

• Example Problem 1: Given moles of a reactant, what are the resulting moles of a product?

  • Use mole ratios from balanced equations.

• Example Problem 2: Given grams of a reactant, how many grams of a product can be formed?

  • Requires conversion from grams to moles, then use stoichiometry to find grams of product.

Summary of Steps for Stoichiometry Problems

1. Start with the given information.
2. Set up a dimensional analysis conversion factor.
3. Cancel units accordingly.
4. Perform calculations, ensuring to account for significant figures.

Conclusion

• Understanding these basic principles and practicing problems will enhance your skills in stoichiometry.
• Upcoming videos will cover limiting reactant stoichiometry and additional practice problems.