1 / 10

Acid-Base Titration

Acid-base titration is a quantitative analysis technique used to determine the concentration of an acid or base in a solution. The equivalence point is where the amount of acid equals the amount of base, resulting in complete neutralization. While this point is fixed, the shape of the titration curve may vary based on acid strength. Indicators, like phenolphthalein, change color at specific pH levels, aiding in detecting the endpoint. Understanding these concepts is crucial for precise titration methods and accurate results.

zoie
Télécharger la présentation

Acid-Base Titration

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. Acid-Base Titration

  2. Acid-Base Titration HnA + n OH-n A- + n H2O Equivalence Point : The point at which the reaction is just complete End Point : The place where experimentally the reaction is observed to be complete

  3. • At Equivalence Point : A solution initially containing [A-] moles of HA, now contains an equivalent amount of A-. • The amount of base needed to reach the equivalence point is independent of the strength of the acid. THE WHOLE BASIS OF TITRATION RELYS ON THIS FACT!

  4. • Although, the location of the equivalence point does not change, the shape of the curve does change.

  5. Observing the equivalence point • • There are as many equivalence points as there are replaceable hydrogens in an acid. • • Some equivalence points MAY • occur without a noticeable rise in pH! • • Two requirements are necessary • for a jump in pH to occur. • The successive Ka values must • differ by several orders of • magntude • 2. The pH of the equivalence point • must not be very high or very low.

  6. Observing the equivalence point – I knew there was a use to studying calculus!

  7. Detecting the equivalence point • pH Measurements are the most direct way of measuring the equivalence point • Less exacting methods include using an indicator dye, which is it self an acid or a base. The protonated and deprotonated forms have different colors, and the pKa should be close to the pH expected at the equivalence point. • The observed color changes of an indicator changes slowly over 1.5 to 2 pH units. • Indicators are therefore only useful in titrations of acid and bases that show definite breaks in the titration curve.

  8. Common acid-base indicators

  9. Phenolphthalein H2In In2− In(OH)3− < 0 0−8.2 8.2−12.0 >12.0 colorless pink to fuchsia colorless

More Related