1 / 13

Chapter 9: Stoichiometry

Chapter 9: Stoichiometry. A. Introduction to Stoichiometry: Stoichiometry – the calculation of an unknown quantity of a substance from a known value of a different substance in a chemical reaction

lei
Download Presentation

Chapter 9: Stoichiometry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 9: Stoichiometry A. Introduction to Stoichiometry: • Stoichiometry – the calculation of an unknown quantity of a substance from a known value of a different substance in a chemical reaction - like mole conversions, except the coefficients in the rxn. matter - coefficients = # of moles - 1 mole = molar mass = 6.02 x 1023 particles = 22.4 L

  2. Stoichiometry is like a recipe: • Reactants = Ingredients • Products = What the recipe makes • Limiting reagent – reactant that determines how much product can be made (used up first) • Excess reagent(s) – reactant(s) not all used up ex. Brownies (makes 24) 2 cups of mix 3 eggs ¼ cup oil

  3. Stoichiometry is like a recipe (cont.): ex. 2 mix + 3 eggs + ¼ oil  24 brownies If you had 2x the ingredients, how many brownies? 48 brownies If you had 96 brownies, how many eggs? 12 eggs If you have 4 cups mix, 4 eggs, ½ cup oil, what is the limiting reagent? the eggs (need 6, only have 4)

  4. B. Mole-Mole Stoichiometry: • Balance equation (if not done) • Start with given (in moles, in this case) • Multiply by mole ratio (coefficients from rxn.) • Include all units and substance in your work! ex. 4Al + 3O22Al2O3 How many moles of aluminum oxide can be produced from 6 moles of oxygen? 6 moles O2 x 2 moles Al2O3 = 3 moles O2 4 moles Al2O3

  5. ex. 6NaOH + Fe2(SO4)3 3Na2SO4 + 2Fe(OH)3 How many moles of Fe(OH)3 are produced from reacting 8 moles of NaOH? How many moles of Fe2(SO4)3 are reacted to form 1.7 moles of Na2SO4? 8 moles NaOH x 2 moles Fe(OH)3 = 2.67 moles of 6 moles NaOH Fe(OH)3 1.7 moles Na2SO4 x 1 mole Fe2(SO4)3 = 0.57 moles of 3 moles Na2SO4 Fe2(SO4)3

  6. C. Volume-Volume Stoichiometry: • 1 mole = 22.4 L of any gas at STP • Start with given (in L, in this case) • Convert given (L) to moles • Multiply by mole ratio (converts moles of given to moles of find – use coefficients from rxn.) • Convert moles of find back to L • Cancel out same units, substances, and numbers • Solve problem

  7. ex. 2SO2 + O2 2SO3 How many liters of oxygen are needed to produce 19.8 L of sulfur trioxide? 19.8 L SO3 x 1 mol SO3 x 1 mol O2 x 22.4 L O2 22.4 L SO3 2 mol SO3 1 mol O2 19.8 L SO3 x 1 mol O2 2 mol SO3 Answer:9.9 L O2

  8. ex. 2NO + O2 2NO2 How many liters of nitrogen monoxide are needed to react with 5.6 L of oxygen to produce nitrogen dioxide? 5.6 L O2 x 1 mol O2 x 2 mol NO x 22.4 L NO 22.4 L O2 1 mol O2 1 mol NO 5.6 L O2 x 2 mol NO 1 mol O2 Answer:11.2 L NO

  9. D. Mass-Mass Stoichiometry: • 1 mole = molar mass (use masses from the P.T.) • Start with given (in grams, in this case) • Convert given (grams) to moles (calculate the molar mass) • Multiply by mole ratio • Convert moles of find back to grams • Cancel out same units and substances • Solve problem

  10. ex. 2SO2 + O2 2SO3 How many grams of oxygen are needed to produce 19.8 g of sulfur trioxide? 19.8 g SO3 x 1 mol SO3 x 1 mol O2 x 32.0 g O2 80.1 g SO3 2 mol SO3 1 mol O2 SO3 = 80.1 g/mole O2 = 32.0 g/mole Answer:3.96 g O2

  11. ex. 2NO + O2 2NO2 How many grams of nitrogen monoxide are needed to react with 5.6 g of oxygen to produce nitrogen dioxide? 5.6 g O2 x 1 mol O2 x 2 mol NO x 30.0 g NO 32.0 g O2 1 mol O2 1 mol NO Answer:10.5 g NO

  12. E. Mixed Stoichiometry Problems: • Uses moles, liters, grams and/or molecules • Start with given • Convert given to moles (unless given is in moles) • Multiply by mole ratio • Convert moles of find to unit of find in problem (unless find is in moles) • Cancel out same units and substances • Solve problem

  13. ex. 2NO + O2 2NO2 How many liters of nitrogen monoxide are needed to react with 8.2 g of oxygen to produce nitrogen dioxide? 8.2 g O2 x 1 mol O2 x 2 mol NO x 22.4 L NO 32.0 g O2 1 mol O2 1 mol NO Answer:11.48 L NO

More Related