1. Learning Objectives Perform stoichiometric calculations to determine – Mass relationships between products and reactants Stoichiometric Calculations

2.  How would you balance the following equation? Fe(s) + O 2 (g) → Fe 2 O 3 4Fe(s) + 3O 2 (g) → 2Fe 2 O 3 (s) *The coefficients represent the number of moles of particles *The number of moles of each substance in a chemical equation are related by the ratio of the coefficients of each substance

3. Using the previous balanced equation, how many moles of oxygen are required to produce 6 moles of Iron (III) oxide?

4. Stoichiometry – mathematical conversions between amounts of substances in chemical reactions Stoichiometry is used to determine – Mass of each substance in a chemical reaction Amount of product produced Amount of reagent consumed – Which reagent limits the amount of product produced – If the expected amount of product was produced Overall mass is conserved in chemical reactions Stoichiometry

5. For stoichiometric calculations, you need – Amount of at least one substance – Mole ratios between substances Found in the balanced chemical equation – Coefficients indicate the number of moles of the substance they precede – Subscripts indicate the number of moles of particles they are behind Ex) 2H 2 + O 2  2H 2 O Reaction requires two moles of H 2 for every one mole of O 2 to form two moles of H 2 O Every mole of H 2 contains two moles of hydrogen atoms Every mole of O 2 contains two moles of oxygen atoms Every mole of H 2 O contains two moles of hydrogen atoms and one mole of oxygen atoms Stoichiometric Calculations

6. Different substances can only be directly related through mole ratios – To convert between mole amounts of two substances, use mole ratios found in the balanced chemical equation as conversion factors – To convert between grams and moles of a substance, use molar mass as a conversion factor Mass Relationships Between Products and Reactants Mole B Molar Mass Gram B Mole RatioMolar Mass Mole AGram A

7. Ex) gramgram — How many grams of H 2 O are produced when 10.0 g of O 2 react according to the reaction 2H 2 + O 2  2H 2 O? Mass Relationships Between Products and Reactants Mole B Molar Mass Gram B Mole RatioMolar Mass Mole AGram A

8. Stoichiometric mole-to-mole conversions  How can you determine the number of moles of hydrogen produced when 0.0400 moles of potassium is used? 2K(s) + 2H 2 O(l) → 2KOH(aq) + H 2 (g)

10. Stoichiometric mole-to-mole conversions  Sulfuric acid is formed when sulfur dioxide reacts with oxygen and water. Write the balanced chemical equation for the reaction. If 12.5 mol SO 2 reacts, how many mol H 2 SO 4 can be produced? How many mol O 2 is needed?

12. Stoichiometric mole-to-mass conversions Determine the mass of sodium chloride or table salt (NaCl) produced when 1.25 moles of chlorine gas reacts vigorously with sodium. Na(s) + Cl 2 (g) → NaCl(s)