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# Chapter 9 stoich

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### Chapter 9 stoich

1. 1. Chapter 9- Stoichiometry: <ul><li>Stoichiometry is like following a recipe </li></ul><ul><li>Focuses on mass or molar relationships </li></ul><ul><li>Key is a balanced equation and reading the equation in terms of… Coefficients </li></ul>I have a yellow hat on! The mass relationships between reactants and products in a chemical reaction.
2. 2. Let’s try this: <ul><li>Type of reaction? </li></ul><ul><li>Balanced equation </li></ul><ul><li>How is this read in terms of moles? </li></ul><ul><li>What are all the possible mole ratios? </li></ul><ul><li>“ RECIPE” for moles to moles, moles to mass, mass to moles and mass to mass </li></ul>Na + Cl 2
3. 3. Let’s try this: <ul><li>Type of reaction? </li></ul><ul><li>Balanced equation </li></ul><ul><li>How is this read in terms of moles? </li></ul><ul><li>What are all the possible mole ratios? </li></ul><ul><li>“ RECIPE” for moles to moles, moles to mass, mass to moles and mass to mass </li></ul>Na + Cl 2 NaCl
4. 4. Let’s try this: <ul><li>Type of reaction? Synthesis </li></ul><ul><li>Balanced equation </li></ul><ul><li>How is this read in terms of moles? </li></ul><ul><li>What are all the possible mole ratios? </li></ul><ul><li>“ RECIPE” for moles to moles, moles to mass, mass to moles and mass to mass </li></ul>Na + Cl 2 NaCl
5. 5. Let’s try this: <ul><li>Type of reaction? Synthesis </li></ul><ul><li>Balanced equation </li></ul><ul><li>How is this read in terms of moles? </li></ul><ul><li>What are all the possible mole ratios? </li></ul><ul><li>“ RECIPE” for moles to moles, moles to mass, mass to moles and mass to mass </li></ul>2Na + Cl 2 2NaCl
6. 6. Let’s try this: <ul><li>Type of reaction? Synthesis </li></ul><ul><li>Balanced equation </li></ul><ul><li>How is this read in terms of moles? </li></ul><ul><li>2 moles of Na react with 1 mole of Cl 2 </li></ul><ul><li> to produce 2 moles of NaCl </li></ul>2Na + Cl 2 2NaCl
7. 7. Let’s try this: <ul><li>What are all the possible mole ratios? </li></ul><ul><li> 2 mol Na 2 mol Na 1 mol Cl 2 </li></ul><ul><li> 1 mol Cl 2 2 mol NaCl 2 mol NaCl </li></ul><ul><li>2 mol NaCl 2 Mol NaCl 1 mol Cl 2 </li></ul><ul><li> 2 mol Na 1 mol Cl 2 2 mol Na </li></ul>2Na + Cl 2 2NaCl
8. 8. Let’s try this: <ul><li>5. “RECIPE” for moles to moles, moles to mass, mass to moles and mass to mass </li></ul><ul><li>Remember that you cannot use a mass-mass </li></ul><ul><li>ratio. You must convert to mol first and then </li></ul><ul><li>back into grams. </li></ul>2Na + Cl 2 2NaCl
9. 9. Conversions of Quantities in Moles <ul><li>CO 2 + 2LiOH -> Li 2 CO 3 + H 2 O </li></ul><ul><li>How many moles of lithium hydroxide are </li></ul><ul><li>required to react with 20 moles of carbon </li></ul><ul><li>dioxide, the average amount exhaled by a </li></ul><ul><li>person each day? </li></ul>
10. 10. Conversions of Quantities in Moles <ul><li>CO 2 + 2LiOH -> Li 2 CO 3 + H 2 O </li></ul>
11. 11. Conversions of Quantities in Moles <ul><li>CO 2 + 2LiOH -> Li 2 CO 3 + H 2 O </li></ul><ul><li>2 mol LiOH </li></ul><ul><li>1 mol CO 2 </li></ul>
12. 12. Conversions of Quantities in Moles <ul><li>CO 2 + 2LiOH -> Li 2 CO 3 + H 2 O </li></ul><ul><li>2 mol LiOH x mol LiOH </li></ul><ul><li>1 mol CO 2 20 mol CO 2 </li></ul>X
13. 13. Conversions of Quantities in Moles <ul><li>CO 2 + 2LiOH -> Li 2 CO 3 + H 2 O </li></ul><ul><li>2 mol LiOH x mol LiOH </li></ul><ul><li>1 mol CO 2 20 mol CO 2 </li></ul><ul><li> x 40 mol LiOH </li></ul>X =
14. 14. More Practice <ul><li>Use the following equation to determine how many grams of aluminum must be used to produce 5.00 grams of hydrogen gas? </li></ul><ul><li>2 Al(s) + 6 HCl(aq)  2 AlCl 3 (aq) + 3 H 2 (g) </li></ul>
15. 15. Do Now <ul><li>In the reaction P 4 + 5 O 2  2 P 2 O 5 , how many moles of oxygen are consumed each time 0.500 mol of P2O5 is formed? </li></ul><ul><li>Answer: 1.25 mol O 2 </li></ul>
16. 16. Limiting Reagent <ul><li>Let’s pretend we have 7,000,000 hot dogs </li></ul><ul><li>But only 600 hot dog buns </li></ul>X 1,000,000 X 100
17. 17. Limiting Reagent <ul><li>Q- How many hot dogs can you make? </li></ul>
18. 18. Limiting Reagent <ul><li>Q- How many hot dogs can you make? </li></ul><ul><li>A – Only 600 </li></ul>
19. 19. Limiting Reagent <ul><li>Once a reactant is used up, there can </li></ul><ul><li>be no more products produced </li></ul><ul><li>(The substance that is used up first is called the) </li></ul><ul><li>limiting reagent = </li></ul><ul><li>the reactant that limits the amount of the other </li></ul><ul><li>reactant that can be combined and thus the </li></ul><ul><li>product that is produced </li></ul><ul><li>Excess reagent = </li></ul><ul><li>the substance not used up completely </li></ul>
20. 20. Let’s try a problem: <ul><li>HCl + NaOH NaCl + H 2 O </li></ul><ul><li>2 mol 2.5 mol </li></ul><ul><li>Determine the limiting reagent for this reaction. </li></ul><ul><li>(This is done by comparing the 2 given value in </li></ul><ul><li>a ratio.) </li></ul>
21. 21. Let’s try a problem: <ul><li>HCl + NaOH NaCl + H 2 O </li></ul><ul><li>2 mol 2.5 mol </li></ul><ul><li>Pick one of the givens and solve: </li></ul><ul><li> 1 mol HCl x mol HCl </li></ul><ul><li> 1 mol NaOH 2.5 mol NaOH </li></ul><ul><li> x 2.5 mol HCl </li></ul>= =
22. 22. Let’s try a problem: <ul><li>HCl + NaOH NaCl + H 2 O </li></ul><ul><li>2 mol 2.5 mol </li></ul><ul><li>2.5 mol HCl: But what does this mean? </li></ul><ul><li>This means that in order to react ALL </li></ul><ul><li>2.5 mol NaOH, you would need AT LEAST </li></ul><ul><li>2.5 mol HCL. </li></ul><ul><li>But you only have 2 mol HCl, so it LIMITS </li></ul><ul><li>the reaction. Hence: limiting reagent. </li></ul>
23. 23. Percentage Yield <ul><li>Theoretical yield = what you calculate or expect under perfect conditions </li></ul><ul><li>Actual Yield = what you get in the lab </li></ul><ul><li>Percentage Yield = x 100% </li></ul>Actual Yield Theoretical Yield