1 / 14

Lab Activity 1: Total Acidity

Lab Activity 1: Total Acidity. Acidity depends on:. Acid strength in solution (measured by the degree of hydrogen ion (H+) dissociation 1. Strong acids: almost totally dissociates, releasing their hydrogen ions for bonding to other ions (HCl)

natividadbland
Download Presentation

Lab Activity 1: Total Acidity

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. Lab Activity 1:Total Acidity

  2. Acidity depends on: • Acid strength in solution (measured by the degree of hydrogen ion (H+) dissociation 1. Strong acids: almost totally dissociates, releasing their hydrogen ions for bonding to other ions (HCl) 2. Weak acids: Have their H ions strong bonded (only few released) CH3COOH

  3. Concentration of acidic compounds in solution. (expressed in: • %w/w, • %v/v, • ppm, • M (moles/l), • N (Equivalent Weight (EW/Volume) - EW = MW/Valency - Meq (milliequivalents) = Actual weight (W)/ EW - Number of equivalents of an acid or base: eq = N x Volume

  4. Total Acidity • A measure of all the H+ of both dissociated and undissociated acids in solution. • Titratable acidity is used to approximate total acidity. • Titratable acidity can be measured by: 1- reacting the acid present with a base such as NaOH to the end point (equivalence point or neutrality point( at which H+ are equal to OH- in solution) indicated by a color change of an indicator. 2. By a pH-meter

  5. Titrations • SA/SB –equivalence point is neutral. • WA/SB –equivalence point is basic. • WB/SA –equivalence point is acidic.

  6. standard solution (in buret) unknown solution Titration • Titration • A standard solution with a known [ ] (the titrant) is used to determine the [ ] of an unknown solution. • The reaction that occurs is a neutralization reaction.

  7. Titration • Equivalence point • Point in the rxn which equal amounts of H3O+ and OH- exist. • dramatic change in pH • End Point • Point at which a color change is observed. • The equivalence point and end point are not necessarily concurrent.

  8. equivalence point OH- Na+ Na+ OH- OH- Na+ Na+ OH- H+ Cl Cl- H+ H+ Cl- H+ Cl- Titration Curve Titration of a Strong Acid With a Strong Base 14.0 12.0 Solution of NaOH Solution of NaOH 10.0 8.0 pH 6.0 4.0 Solution of HCl 2.0 0.0 0.0 10.0 20.0 30.0 40.0 Volume of 0.100 M NaOH added (mL)

  9. Features of the Strong Acid-Strong Base Titration Curve • The pH starts out low, reflecting the high [H3O+] of the strong acid and increases gradually as acid is neutralized by the added base. • Suddenly the pH rises steeply. This occurs in the immediate vicinity of the equivalence point. For this type of titration the pH is 7.0 at the equivalence point. • Beyond this steep portion, the pH increases slowly as more base is added.

  10. The four Major Differences Between a Strong Acid-Strong Base Titration Curve and a Weak Acid-Strong Base Titration Curve • The initial pH is higher. • A gradually rising portion of the curve, called the buffer region, appears before the steep rise to the equivalence point. • The pH at the equivalence point is greater than 7.00. • The steep rise interval is less pronounced.

  11. For Experimentsfollow the lab manual !!

More Related