1 / 22

Chapter 16

Chapter 16. Acids- Base Titration and pH. Section 16.1. Aqueous Solutions and the Concept of pH. Self Ionization of Water. When two molecules of water produce a hydronium and hydroxide ion by the transfer of a proton. H 2 O + H 2 O   H 3 O + + OH -.

elijah
Download Presentation

Chapter 16

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 16 Acids- Base Titration and pH

  2. Section 16.1 Aqueous Solutions and the Concept of pH

  3. Self Ionization of Water • When two molecules of water produce a hydronium and hydroxide ion by the transfer of a proton. • H2O + H2O  H3O+ + OH-

  4. At 25C the [H3O+] = [OH-]= 10-7 M • So, the products of [H3O+] and [OH-] can be represented by: • [H3O+] x [OH-] • 10-7 M x 10-7 M = 10-14 M2 • Where 10-14 M2 Is the Kw ( ionization constant of water) So, [H3O+] x [OH-]= Kw at 25C

  5. Neutral, Acidic, and Basic Solutions • Neutral solutions: [H3O+] = [OH-]= 10-7 M • Acidic solutions: [H3O+] > [OH-] • Basic solutions: [H3O+] < [OH-]

  6. Calculating the [H3O+] and [OH-] • We can find the [H3O+] and[OH-] by using the formula: • [H3O+] x [OH-]= Kw= 10-14 M2 Practice p: 484

  7. The pH Scale • It is the negative logarithm of the hydronium ion concentration • pH= - log [H3O+]

  8. Likewise, pOH It is the negative logarithm of the hydroxide ion concentration • pOH= - log [OH-] • So, pH + p OH= 14 at 25C

  9. Calculations Involving pH • [H3O+]=10-pH • Practice p: 487

  10. Summary: • 1- [H3O+] x [OH-]= Kw • 2- pH= - log [H3O+] • 3- pOH= - log [OH-] • 4- pH + p OH= 14 at 25C • 5- [H3O+]=10-pH

  11. Section 16.2 Determining pH and Titrations

  12. Indicators and pH Meters • 1- Acid- Base indicators: are compounds whose colors are sensitive to pH. Indicators come in many different colors. The exact pH range over which an indicator changes color also varies.

  13. 2-Universal indicators: the pH of solution can be determined by comparing the color it turns with the scale of paper.

  14. 3- pH meter: determines the pH of a solution by measuring the voltage between the electrodes that are placed in the solution. (It’s the most accurate way to determine the pH)

  15. Titration • Is the controlled addition and measurement of the amount of a solution of known concentration required to react completely with a measured amount of a solution of unknown concentration. • The equation of titration is: • H3O+ + OH-  2H2O

  16. Types of Titration • 1- strong acid- strong base • 2- strong acid- weak base • 3- weak acid- strong base

  17. Indicators are specific, each type of titration needs a specific indicator • For example: • Strong acid- strong base titration: We use bromothymol blue (6.2- 7.6) • For strong acid- weak base titration: We use bromophenol blue ( 3-4.6) • For weak acid- strong base titration We use phenolphtalein(8-10)

  18. Equivalence Point • The point at which the two solutions used in a titration are present in chemically equivalent amounts is called the equivalence point.

  19. End Point • The endpoint in titration marks the point at which the color of indicator changes.

  20. Titration setup

  21. Titration Curves

  22. Molarity and Titration • The solution that contains precisely known concentration of solute is known as the standard solution. • To find the molarity or the volume of an unknown solution we use the equation: • No of moles of acid= No of moles of base • CxV (acid)= CxV (base) • Practice p: 503 (1 and 2)

More Related