1. Stoichiometry

2. What is Stoichiometry?
Stoichiometry is the study of quantitative relationships between the amounts of reactants used and products formed by a chemical reaction; based on the law of conservation of mass.

3. Goals for the unit Write mole ratios from balanced chemical equations
Calculate the number of moles and the mass of a reactant or product when given the number of moles or the mass of another reactant or product
Identify the limiting reactant in a chemical reaction
Determine the percent yield of a chemical reaction

4. Using the following equation, a number of quantitative relationships can be determined
CH4 + O2  H2O + CO2
Balance the equation.
Using the equation, determine the ratio of reactants to products.
Determine the molar ratios.
Determine the molar masses
Use the data to support the Law of Conservation of Mass

5. How do all the molecules relate to one another?
CH O2  2 H2O + CO2
1 mole CH4 1 mole CH4 1 mole CH4
2 moles O2 2 moles H2O 1 mole CO2
2 moles O2 2 moles O2 2 moles O2
1 mole CH4 2 moles H2O 1 mole CO2
2 moles H2O 2 moles H2O 2 moles H2O
1 mole CH4 2 moles O2 1 mole CO2
1 moles CO2 1 mole CO2 1 mole CO2
1 mole CH4 2 moles O2 2 moles H2O

6. Answer the Following Questions:
If 5 moles of CH4 had been used, how many moles of O2 are required?
Answer: 10 moles
If 5 moles of CH4 had been used, how many moles of H2O will be produced? CO2?
Answer: 10 moles of water and 5 moles CO2
If the amount of reactant used totals 30 g, what is the total mass of product that can be produced?
Answer: 30 g
If 120 g of product was produced by reacting 40 g of CH4, how much oxygen must have been used?
Answer: 80 g

7. Interpret the following equation in terms of particles, moles, and grams
4Fe (s) + 3O  2Fe2O3(s) 4 particles + 3 particles -> 2 particles 4 Moles + 3 Moles  2 Moles g g  g g= g Law of the Conservation of Mass is observed because One side of the equation equals the other!