CH302 Chapter 8 notes part 3 polyP update

# CH302 Chapter 8 notes part 3 polyP update - CH302 Chapter 8...

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O H KClO KOH HClO 2 4 4 + + CH302 Chapter 8 notes part 3 Common Ion Effects Titration Curves show (and we can calculate them too!) pH vs. amount of acid or base added using a buret All are using this concept: ACID + BASE SALT + WATER: 1. Strong Acid + Strong Base Titration 2. Weak Acid + Strong Base Titration 3. Strong Acid + Weak Base Titration 4. Weak Acid + Weak Base Titration Each has characteristic titration curves, and specific pH ranges at the endpoint and equivalence points. 1. Strong Acid/Strong Base Titration Curve As an example, consider the titration of 100.0 mL of 0.100 M perchloric acid with 0.100 M potassium hydroxide. In this case, we plot pH of the mixture vs. mL of KOH added. Note that the reaction is a 1:1 mole ratio. We will now calculate the pH at different points: 1: Initial: Before any KOH is added 2: Before the equivalence point: After a total of 20.0 mL 0.100 M KOH has been added 3: Still before the equivalence point: After a total of 50.0 mL of 0.100 M KOH has been added 4: Again, before the equivalence point: After a total of 90.0 mL of 0.100 M KOH has been added 5: At the equivalence point: After a total of 100.0 mL of 0.100 M KOH has been added 6: After the equivalence point: After a total of 150.0 mL of 0.100 M KOH has been added (YOU MIGHT WANT TO BRING SOME SCRATCH PAPER FOR THIS. IT WILL TAKE A WHILE!) Results:

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1 mol 1mol 1mol CH COOH + KOH K CH COO + H O 1mmol 1mmol 1mmol 3 + 3 - 2 2. Weak Acid/Strong Base Titration Curve The As an example, consider the titration of 100.0 mL of 0.100 M acetic acid, CH 3 COOH, (a weak acid) with 0.100 M KOH (a strong base). The acid and base react in a 1:1 mole ratio. CONSIDER THIS: Before the equivalence point is reached, both CH 3 COOH and KCH 3 COO are present in solution forming a buffer. KOH reacts with CH 3 COOH to form KCH 3 COO. This is a weak acid plus the salt of a weak acid - a buffer . so. .. How might buffer production affect the titration curve? Will the pH at the equivalence point will be 7? Will it be above or below 7?
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## This note was uploaded on 03/26/2012 for the course CHEM 302 taught by Professor Mccord during the Fall '10 term at University of Texas.

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CH302 Chapter 8 notes part 3 polyP update - CH302 Chapter 8...

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