Genchem Quiz

• Stoichiometry


  • Allows us to make predictions about the outcomes of chemical reactions
  • The study of the quantitative aspects of chemical reactions

  
• Stoichiometry allows us to make the following predictions:
• Predictions that can be made using stoichiometry

  • Predict the mass of a product of a chemical reaction if given the starting masses of reactants
  • Predict the volume of a gas which will be produced by a reaction if given the starting amounts of reactants
  • Determine the optimal ratio of reactants for a chemical reaction so that all reactants are fully used
• Stoichiometry skills to master

  • Mole to Mole
  • Mole to Mass
  • Mass to Mole
  • Mass to Mass
• Mole to Mole Conversion

  • The ratio between the amounts in mol of any 2 compounds in a balanced equation
  • The given is expressed in mole (mol)
  • The final answer is also expressed in mol
• Mole to Mole Conversion


  • The ratio of reactant 1 to product (1:2 for 1mol of N2 to 2mol of NH3)
  • The ratio of reactant 2 to product (3:2 for 3mol of H2 to 2mol of NH3)
• Mole to Mole Conversion

  1. If 4.25 mole of O₂ react, how many mole of CO₂ could be formed?

  2. How many moles of NH₃ are needed to react with 8 moles of O₂?
• Mole to Mass Conversion


  • The formula mass of a compound will be the conversion factor
  • Get the formula mass of the unknown (?)
  • The given is expressed in mole (mol)
• Mole to Mass Conversion


  If 4.25 mole of O₂ react, how many grams of CO₂ could be formed?
• Mass to Mole Conversion


  • The formula mass of a compound will be the conversion factor
  • Get the formula mass of the given and the unknown (?)
  • The given is expressed in mass
• Mass to Mole Conversion

  If 50.5 g of O₂ reacts, how many moles of H₂O could be formed?
• Mass to Mass Conversion


  • The formula mass of a compound will be the conversion factor
  • Get the formula mass of the given and the unknown (?)
  • The given is expressed in mass
• Mass to Mass Conversion


  If 50.5 g of O₂ reacts, how many grams of H₂O could be formed?
• Take note of the 4 problem patterns: mole to mole, mole to mass, mass to mole, mass to mass
• Try me! Sodium metal burns in the air according to the balanced reaction shown below.

  1. 4Na (s) + O₂ (g) → 2Na₂O (g)

  2. 9.5 g Na

  3. 12.5 g Na₂O
• Limiting Reactant


  The reactant that is totally consumed in a chemical reaction
• Excess Reactant


  The reactant that remains in a chemical reaction
• Theoretical Yield


  • The quantity of the product from a perfect chemical reaction
  • The maximum amount of the product that can be produced from the given amount of reactants
• Percent Yield


  • Measures the effectiveness of a chemical reaction
  • How much of the reactants (in %) were transformed into a product
• Sample Problem 1


  1. If 2.00g Si and 1.50g N₂ react:

  2. Which is the limiting reagent?

  3. What is the theoretical yield in grams?

  4. If 2.89g of product is obtained, then what is the percent yield?
• Sample Problem 2


  1. If 15.0g of CH₃OH reacts with 10.0g of CO, which is the limiting reagent, and what is the theoretical yield of CH₃COOH?

  2. If the actual yield is 19.1g, what is the percent yield?