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Modern Chemistry Chapter 15 Acid-Base Titration and pH

Modern Chemistry Chapter 15 Acid-Base Titration and pH. Sections 1 & 2 Aqueous Solutions and the Concept of pH Determining pH and Titrations. Determining pH and Titration. Chapter 15 Vocabulary. Standard Solution Primary Standard Standardization. Self Ionization pH pOH

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Modern Chemistry Chapter 15 Acid-Base Titration and pH

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  1. Modern ChemistryChapter 15Acid-Base Titration and pH Sections 1 & 2 Aqueous Solutions and the Concept of pH Determining pH and Titrations Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  2. Determining pHand Titration Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  3. Chapter 15 Vocabulary • Standard Solution • Primary Standard • Standardization • Self Ionization • pH • pOH • Acid-base indicator • Transition interval • Titration • Equivalence Point • Endpoint Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  4. Indicators • Acid-base indicators- compounds whose colors are sensitive to pH HIn  H+ + In- p. 511 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  5. Indicators • Transition Interval – the pH range over which an indicator changes color Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  6. Color Range of Indicators p. 513 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  7. Color Range of Indicators p. 513 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  8. Color Range of Indicators p. 513 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  9. pH of Common Materials p. 512 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  10. pH Meter • Determines the pH of a solution by measuring the voltage between two electrodes that are placed in a solution Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  11. How does a pH meter work? In 1901 a German chemist named Fritz Haber discovered that the voltage at certain glass surfaces changed in a regular manner with the acidity of a solution. Modern pH sensing electrodes are a refinement of this fundamental discovery. The pH electrode consists of a thin membrane of Hydrogen sensitive glass blown on the end of an inert glass tube. Because this is a special type of glass and very thin, the bulb is very fragile and great care must be exercised in handling it. This tube is filled with an electrolyte, and the signal is carried through Ag/AgCL wire. This is a pH half cell. Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  12. Titration • The controlled addition and measurement of the amount of a solution of known concentrationrequired to react completely with a measured amountof a solution of unknown concentration. • A quantitative lab procedure to determine concentration or amount. Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  13. Doing a Titration p. 518 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  14. Doing a Titration p. 518 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  15. Doing a Titration p. 518 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  16. Doing a Titration p. 519 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  17. Doing a Titration p. 519 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  18. Doing a Titration p. 519 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  19. Titration Video Glencoe Disc 3 Insert Holt Disc 2 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  20. Titration • Equivalence point – the point at which the two solutions in a titration are chemically equivalent. • MOLESbase = MOLESacid • If the coefficients are all 1 then the mole ratio has no effect so… • MB xLB = MA xLA M = mol/Lmol = MxL Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  21. Titration STANDARD SOLUTION IN BURETTE DATA 25 0.2M mL of base known concentrationof base mL of acid unknown concentrationof acid 10 X M IN FLASK ANALYTE Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  22. Equivalence Points Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  23. Equivalence Point & Endpoint • Endpoint – the point in a titration at which an indicator changes color. If the equivalence point is 7, what is the best indicator to use? Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  24. Titration Curve p. 517 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  25. Titration Curve p. 517 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  26. Standardization • Standard solution – a solution that contains the precisely known concentration of a solute. • The standard solution has be “standardized” (determined its concentration) with a “primary standard” (a solution with a known concentration). Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  27. Molarity & Titration M = mol/Lmol = MxL • MOLESbase = MOLESacid • Calculate the moles of the substance in which you know the molarity and concentration. • Use the mole ratio to convert these moles to moles of the other substance. • Now that you have moles of the other substance divide by liters of that substance to get molarity. Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  28. Sample Problems p.520 In a titration, 27.4 mL of 0.0154 M Ba(OH)2 is added to a 20.0 mL sample of HCl solution of unknown concentration until the equivalence point is reached. What is the molarity of the acid solution? 4.22 × 10−2 M HCl Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  29. Molarity & Titration • Calculate the moles of the substance in which you know the molarity and concentration. 0.0154 M Ba(OH)2 x 0.0274 L Ba(OH)2 =0.000422 moles Ba(OH)2 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  30. Molarity & Titration 2. Use the mole ratio to convert these moles to moles of the other substance Ba(OH)2 (aq) + 2HCl (aq) BaCl2 (aq) + 2HOH (l) 2 mole HCl x 1 moles Ba(OH)2 MOLE RATIO (coefficients) = 0.000844 moles HCl Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  31. Molarity & Titration • Now that you have moles of the other substance divide by liters of that substance to get molarity. 0.000844 moles HCl 0.0200 L HCl = 0.0422 M HCl Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  32. Practice Problems p.521 • 1. A 15.5 mL sample of 0.215 M KOH solution required 21.2 mL of aqueous acetic acid solution in a titration experiment. Calculate the molarity of the acetic acid solution. • 2. By titration, 17.6 mL of aqueous H2SO4 neutralized 27.4 mL of 0.0165 M LiOH solution. What was the molarity of the aqueous acid solution? 1. 0.157 M CH3COOH 2. 0.0128 M H2SO4 Chapter 15 Sec 2 Determining pH & Titration p. 511-521

  33. Ch 15 Sec 2 Homework Titration Calculations Worksheet Chapter 15 Sec 2 Determining pH & Titration p. 511-521

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