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Stoichiometry

Stoichiometry. “Calculating Quantities in Reactions”. The coefficients in a balanced chemical equation represent the numbers of particles for each substance in the reaction. 2H 2 + O 2  2H 2 O

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Stoichiometry

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  1. Stoichiometry “Calculating Quantities in Reactions”

  2. The coefficients in a balanced chemical equation represent the numbers of particles for each substance in the reaction. 2H2 + O2 2H2O • For this equation, the coefficients show that _____ molecules of hydrogen react with _____ molecules of oxygen to yield _____ molecules of water. Balanced Equations Show Proportions

  3. Just as you can interpret these equations in terms of particles, you can interpret them in terms of moles. • The coefficients in a balanced equation also represent the moles of each substance. 2C8H18 + 25O2 16CO2 + 18H2O How many moles of octane react? ______________ How many moles of oxygen react? ______________ How many moles of CO2 are produced? ______________ How many moles of water are produced? ______________ Amounts in Moles

  4. Stoichiometry – the proportional relationship between two or more substances during a chemical reaction. • You will soon be able to determine how much of a product is formed from a given quantity of reactant. • The mole ratio is the key. • The coefficients are ratios or conversion factors to convert between reactants and products. These ratios are called MOLE RATIOS Mole Ratios in a Rxn

  5. Consider the following reaction: • Phosphoric Acid neutralizes Barium Hydroxide  ?? • What is the molar ratio of acid to base? __________. • Base to salt? __________. Acid to salt? __________. • Base to acid? __________. Water to acid? __________. • Water to base? __________. Base to water? __________. Practice With Mole Ratios

  6. The mole ratios are in ____________, obviously. • You may ONLY convert between reactants and products through MOLES using the mole ratio as a conversion factor. • Make a T-Chart and solve just as we have done in the past Making Calculations

  7. Molar mass of “B” (in grams) # of moles of “B” Grams of “A” 1 mole of “A” Molar mass of “A” (in grams) # of moles of “A” 1 mole of “B” This process enables us to convert from one reactant to another, one reactant to a product, or one product to another using the molar ratios from the balanced chemical equation. Molar Ratio of “A” to “B” Order of Operations

  8. How many moles of water can be produced by the combustion of 2.45 moles of propane? Step 1: Write out the balanced reaction. Step 2: Determine the molar ratio or the starting component and the ultimate component. Step 3: Make a chart of relationships and solve. Practice With Stoich

  9. Convert 0.85 moles of oxygen gas to grams of oxygen gas. • Convert 12.54 grams of pentane (C5H12) to moles of pentane Practice with Conversions

  10. How many grams of oxygen are required to burn 12.54 grams of pentane (C5H12) to completion? Practice with Conversions

  11. ___POCl3(l) + ___H2O(l) ___H3PO4(l) + ___HCl(g) • How many grams of hydrochloric acid will be produced from the consumption of 18.45 grams of POCl3? Stoichiometry Problems

  12. 1 POCl3(l) + 3 H2O(l) 1 H3PO4(l) + 3 HCl(g) • How many grams of hydrochloric acid will be produced from the consumption of 18.45 grams of POCl3? • How many grams of phosphoric acid will be produced with this quantity of POCl3? Stoichiometry Problems

  13. What volume of H3PO4 forms when 56 mL POCl3 completely react? (density of POCl3 = 1.67 g/mL; density of H3PO4 = 1.83 g/mL) 1 POCl3(l) + 3 H2O(l) 1 H3PO4(l) + 3 HCl(g) More Practice

  14. How many grams of C5H8 form from 1.89x1024 molecules C5H12? C5H12(l) C5H8(l) + 2H2(g) Using Molecules

  15. Get started on your homework packet “Calculating Quantities in Reactions” • This will be homework and is due tomorrow 

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